Anacardiaceae

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Anacardiaceae

Description

Trees, erect or scandent shrubs, or climbers, very rarely epiphytic shrubs; Leaves often crowded at the (thickened) end of twigs, spiral or alternate (only opposite or decussate in Bouea), sometimes subverticillate; Stipules absent. Inflorescences terminal and/or axillary, rarely cauliflorous, paniculiform (panicles or thyrses), sometimes racemose or spiciform, rarely flowers solitary; Flowers regular, bisexual, or unisexual by abortion (plants monoecious, dioecious, or polygamous). Petals 5 or 4, or 0 (in Pistacia), free, sometimes the basal part longitudinally adnate to the floral axis, imbricate or valvate, rarely contorted, caducous or persistent, sometimes accrescent (Swintonia & Gluta spp.). Stamens equal or twice the number of calyx lobes or petals, rarely more or ∞ (Gluta spp.), inserted on the margin of disk, or just outside or inside of this margin, or on an enlarged torus (Gluta); Ovary free, or the basal part connate with disk or receptacle, superior, sometimes partly or wholly immersed in disk or receptacle and seemingly semi-inferior or inferior (Pegia, Melanochyla & Semecar-pus spp.), rarely really inferior (Drimycarpus & extra-Mal. Holigarnd), usually sessile, sometimes stiped (Gluta); Ovule 1 in each carpel or cell, pendulous, apotropous. Fruits drupaceous, sometimes subtended by enlarged calyx lobes (Parishia) or petals (Swintonia & Gluta spp.), or an enlarged fleshy hypocarp (pedicel, receptacle; in Anacardium & Semecarpus), l-5(-12)-celled, l-5(-12)-seeded; Seed exal-buminous or with scanty endosperm, rarely labyrinthine (Mangifera spp.);

Distribution

Africa:, Seychelles (Seychellespresent) Asia Minor: present Asia-Tropical:, Borneopresent; Malayapresent; Sumatera (Sumaterapresent); Thailand (Thailandpresent) Australasia: Borneo and other islands: present Canary Is: present Ceylon: present Continental SE. Asia: present Fiji Is: present Indo-Malesia: present Latin America: present Madagascar: present Melanesia: present Micronesia: present New Britain: present New Caledonia: present North and Central America: present Northern America:, Texas (Texaspresent) Pacific:, Fiji (Fijipresent) Pacific Is: present Polynesia: present SE.-E. Asia: present Solomon Is: present Solomons: present West Malesia: present continental Asia: present temperate zone: present temperate zones of both hemispheres: present the Mediterranean: present throughout the tropics and subtropics: present tropical America: present tropical Asia: present villages in Malaya: present
About 70 genera with c. 600 spp., distributed chiefly throughout the tropics and subtropics. Malesia is the richest major tropical area for this family, with more genera represented than in any other area; even though Rhus is not richly represented in species.
Within Malesia occurrence is mainly in West Malesia. The richest endemic development is in Malaya and Borneo; as usual Sumatra has a fair number of species but few endemics. , .
Only few genera occur in the temperate zone, e.g. Rhus, which is largely warm-temperate; Pistacia is mainly extra-tropical, but occurs with a few species in the tropics.
Species of several genera are widely cultivated for their fruit, viz Anacardium, Bouea, Mangifera, and Spondias. They may run wild and become naturalized, e.g. Anacardium, the cashew nut, which is according to CORNER common in villages in Malaya, especially on the East Coast, where it is so thoroughly established to appear indigenous. The same holds for cultivars or semi-domesticated forms of Mangifera, Spondias, etc. in Borneo and other islands. For this reason it is in some cases even impossible to establish with certainty the really indigenous occurrence of some species, especially if they are found both in continental SE. Asia and in Malesia.
Of the genera treated here Anacardium and assumedly Lannea are definitely introduced and naturalized.
Androtium, Koordersiodendron, and Melanochyla are confined, so far known, to Malesia. Bouea, Drimy'carpus,Parishia, Pegia, and Swintonia are found in Malesia and continental SE. Asia.
Most of the following genera occur in the southeastern part of continental Asia and Malesia with only one or a few species distributed in other areas: Buchanania (also found in Australia and as far east as in Polynesia), Dracontomelon (also occurring in Solomon Is., eastwards to the Fiji Is.), Gluta (with also 1 sp. found in Madagascar), Mangifera and Pentaspadon (distributed as far east as the Solomon Is.), and Semecarpus (also occurring in Australia, Micronesia, Melanesia, and as far east as the Fiji Is.).
Lannea is chiefly an African genus with only 1 sp. recorded to occur in tropical Asia, and obviously introduced in Malesia. The big genus Rhus (sensu lat.: c. 150 spp.) occurs mainly in the warm-temperate zones of both hemispheres and extends also into the tropics; there are 8 spp. of it in Malesia.
Spondias appears to have two centres of distribution: tropical America and Indo-Malesia.
Each of the following two small genera has only one species in Malesia: Pleiogynium consists of c. 3 spp. distributed in the Pacific Is., Fiji, Solomons, Australia, and Malesia, and Euroschinus has 6 spp.: 4 in New Caledonia, one in Australia, and one in New Britain and Malesia.
The following two genera, each consisting of c. 10 spp., have a rather wide and interesting distribution. Campnosperma is known from Madagascar, the Seychelles, Ceylon, Thailand through Malesia (with 5 spp.), Micronesia&Melanesia, and Latin America. Pistacia is dis-junctly distributed in the Canary Is., the Mediterranean, Asia Minor, SE.-E. Asia, Malesia (with 2 spp.), and North and Central America (Texas; Mexico).
Anacardium is an American genus and one of its species, A. occidentale, is widely cultivated in the tropics and naturalized in places.

Ecology



Climatic conditions. Most Malesian Anacardiaceae are constituents of the primary rainforest, but quite a number tolerate or even prefer a seasonal climate; for example Semecarpus heterophyllus is very common in the teak forests in Java. Lannea coromandelica is also characteristic for a seasonal climate. Also for the cultivation of the better species of Mangifera a seasonal climate is more suitable.

During the dry season these species are frequently leaf-shedding, flowers and young foliage appear on the bare branches with the onset of the rainy season.

A deciduous habit occurs in proportionally many Anacardiaceous genera, e.g. in some spp. of Gluta (G. pubescens, G. malayand), in Parishia, some spp. of Spondias, and in most spp. of Rhus and Pentaspadon. In most cases the deciduous habit is not especially bound to a distinct seasonal climate; a small decrease in rainy days or a prolonged dry spell seems also under everwet rainforest conditions a sufficient impetus.

Substratum. Several species are characteristic constituents of swamp- and peat-forests, tidal riverbanks or temporary overflowed areas or swamps, e.g. Androtium astylum, Campnosperma spp., Gluta renghas, G. velutina, Mangifera gedebe, Melanochyla auriculata, Pentaspadon motleyi (), Swintonia glauca, etc. Trees of such permanently or temporarily inundated habitats may produce prominent buttresses. But large buttresses may also occur in dryland species, e.g. in Spondias pinnata, Koordersiodendron pinnatum, Gluta malayana (), and Dracontomelon dao (). Other genera may lack buttresses in all species, e.g. Mangifera, although M. gedebe is a true swamp-forest species.

A few swamp-forest species may have stilt-roots, e.g. Melanochyla bracteata (), M. auriculata, and Gluta velutina (). Campnosperma coriaceum develops in deep swamps apart from prop-roots slender-kneed pneumatophores or loop-roots over 1 m high (). Also in deep swamps Gluta renghas develops a conically thickened stem-base ().

One species, Pentaspadon curtisii, is confined to limestone; other species may sporadically occur on this bedrock.

Of Semecarpus one species, S. stenophyllus, is from the Philippines recorded to be confined to streambeds. As usual with such rheophytic plants, growing on gravel and rocks along mostly swift-running streams at low altitude and subject to sudden overflow, it has the stenophyllous habit.

Habit. As to habit, most Malesian species are trees of small to medium size, but spp. of Gluta, Buchanania, Bouea, Dracontomelon, Mangifera, Koordersiodendron, Parishia, Spondias and Swintonia can attain large sizes, sometimes with massive crowns, and reach a height of 30-55 m and a stem diameter of ¾-1(-1½) m.

The only true genus of lianas is Pegia.

Climbing habit has also been mentioned in some Rhus and Semecarpus spp. which are recorded either as a shrub or as an epiphyte. This observation of variable habit is also recorded from Spondias philippinensis, which is even cited to be a shrub, a small tree, a liana, an epiphyte, and a big tree. This variability is doubtless due to the fact that these species may be erect and terrestrial, but may also begin their life as a 'hemi-epiphyte', which means that they start as an epiphyte and by sending roots down along a host tree may reach the soil and become terrestrial and may eventually outlive their host tree. This change of habit has been described for species of several other rainforest genera, Vaccinium, Fagraea, Ficus, and others, and has been described and explained in full for Wightia (Scroph.) by VAN STEENIS ().

Some species of Semecarpus exhibit a characteristic cycadoid or 'Schopfbaum' habit, that is: they remain unbranched for a long time and carry an apical tuft of large, often sessile pseudo-whorled leaves, as a sort of nest; sometimes they produce several such nests in succession. This is characteristic for Semecarpus magnificus and S. nidificans in Papua, the latter's epithet being even derived from this peculiar habit. Also young plants of S. bunburyanus and S. curtisii () show this growth mode.

Pollination

The plants of most species in this family are dioecious or polygamous and bear many-flowered inflorescences. The flowers possess nectary organs or disks and are sometimes fragrant. They are cross-pollinated and are evidently entomophilous.

Dispersal

The fruits of Anacardiaceae are drupaceous and vary considerably in size: from less than 1½ cm long (e.g. in Buchanania, Campnosperma, Euroschinus, Rhus, etc.) to 25 cm (e.g. in Mangifera); embryos of some species of the latter genus belong to the largest in the world. The drupes or sometimes their stones (endocarps) have been reported to be dispersed in various ways.

Some fruits are eaten and dispersed by birds and/or other animals (bats, squirrels, monkeys, elephants, etc.). In Djambi (Central Sumatra) the fruiting season is Jan.-Febr., attracting game, pigs, elephants, etc. By end March RUTTEN (, fig.) observed numerous seedlings of Durio and Mangifera odorata (ambatjan) in the excrements of elephants. ASHTON told me that he saw squirrels in Sarawak eating the fruits of Dracontomelon. Sometimes one would find plenty of the fruits under the tree with only part of the pulp eaten; pigs consumed such dropped fruits, but the hard stones, which remained internally intact, were carried away and thus disseminated.

Also fruits may be washed away to some distance by rain into places suitable for germination and growth. Some species of Dracontomelon, Campnosperma, Gluta, etc. growing in peat-swamp forests, on tidal riverbanks or occasionally in inundated areas, are dispersed by water. Fruits of the cultivated Anacardium and Spondias were found drifting along the sea-coast or floating in the sea.

Many species of Parishia (), Gluta (incl. Melanorrhoea), and Swintonia () bear fruits possessing rather long accrescent calyx lobes or (wing-like) petals sometimes reaching more than 10 by iy4 cm. Such winged fruits turn upside-down when they fall from the tree and rotate away in their descent (cf. ).

Except for the small-fruited drupaceous genera which may be carried by birds over some distance, there are no devices leading to accept long-distance dispersal in Anacardiaceae, except that fruit of swamp inhabiting species may be carried by the water of rivers.

Morphology

Domatia. As exposed by JACOBS () domatia are usually found in or near the axils of nerves on the undersurface of leaves or leaflets in some species of the following genera: Dracontomelon, Pegia, Pentaspadon, Pleiogynium, and Rhus. They appear as pits or cavities and are usually roofed over by hairs. , , . Their presence or absence in some taxa of the Anacardiaceae can sometimes be used as a supporting character for distinguishing related genera or species, which is especially useful in naming sterile material.

Domatia are marsupiform (i.e. pocket-shaped) in Pleiogynium timorense and Anacardium occidentale, and some African spp. of Lannea; marsupiform-lebetiform (between basin- and pocket-shaped) in Pentaspadon motleyi; lebetiform (with a basin-shaped cavity) in Pleiogynium timorense; cavernose in Swintonia schwenkii; or consist of axillary hair tufts in Dracontomelon.

Indumentum. Besides normal hairs, scales occur in Campnosperma and stellate hairs are found in Lannea and some Semecarpus spp. In Melanochyla and Semecarpus papillae are a feature of the underside of the leaves ().

Venation. Besides the normal reticulate veins there occur in several species reticulate-scalari-form venation or clear crossbar veins. A marginal nerve or intramarginal vein is found in the leaves of e.g. Drimycarpus and some species of Spondias, respectively, while in Buchanania between each pair of nerves an intermediary vein (shorter than the nerves but parallel to them) is found, here called 'internerval vein'. In most genera the areolae have one dendroid vein; in Rhus there are no areolae as the veins end blind.

Unifoliolate leaves. In Rhus leaves are almost always compound, but R. borneensis has simple leaves, without any trace of articulation. In R. linguata leaves are also simple but clearly unifoliolate with a distinct articulation at the apex of the petiole.

Teratology. COSTERUS & SMITH () recorded a seed of Mangifera indica having germinated within the fruit and one double-fruit of Mangifera sp. MASTERS () found the following terata in the seeds of Mangifera indica: (a) the complete absence of one of the cotyledons, (b) the plumule in the one case giving off no shoot at all, in the other giving rise to three shoots from its side, and (c) the production of adventitious roots from the 'scooped-out' portion of the cotyledon.

In Mangifera decandra I observed one stamen with the filament broadened gradually at about the upper half and the anther attached on one side (cf. ). In Euroschinus papuanus two stamens were found with their filaments united.

Anatomy

Most relevant anatomical data on the Malesian Anacardiaceae are given for the wood by DADSWELL & INGLE (1948) and for the leaf by WILKINSON (1971) (the results of her thesis together with additional observations will be published later in separate instalments). The wood anatomy of Androtium and Pegia is unknown, as well as the leaf anatomy of Pegia. Of the other genera usually only a small portion of the species has been investigated anatomically.

Characteristic wood anatomical features of the family are large, half-bordered to almost simple, rounded to irregularly shaped, vessel-ray pits (in all Malesian genera), simple to minutely bordered pits to the fibres, and the presence of horizontal gum- or resin-canals in the rays of most genera (but not in Anacardium, Bouea, Dracontomelon, Drimycarpus, Mangifera p.p., Rhus, and Semecarpus). Vessel perforations are exclusively simple except in Campnosperma in which they are partly scalariform, and in Euroschinus in which they are occasionally reticulate.

The fibres are predominantly septate in Dracontomelon, Koordersiodendron, Lannea, Pentaspadon, and Spondias; only sparsely septate in Anacardium, Buchanania p.p., Campnosperma, Euroschinus, Pleiogynium, and Rhus p.p.; and non-septate in the remaining Malesian genera studied thoroughly so far. The rays are usually narrow (however, in some genera up to 5-7 cells wide) and clearly heterogeneous, except in Gluta (including Melanorrhoea) and Swintonia in which they are weakly heterogeneous to homogeneous. Siliceous inclusions have been noted in the rays of Gluta s.l., Parishia, and Swintonia. Solitary crystals are of common occurrence in the rays of most genera, whilst they occur only rarely in the axial parenchyma of a few genera. The parenchyma is typically paratracheal, but additional apotracheal bands occur in Bouea, Gluta s.l., Mangifera, and Swintonia. The paratracheal parenchyma is aliform to confluent in Anacardium, Buchanania, Dracontomelon, Drimycarpus, Koordersiodendron, Melanochyla, Pleiogynium, Semecarpus, and Spondias. It is more scanty, vasicentric in Campnosperma (± absent), Euro-schinus, Lannea, Parishia, Pentaspadon, Pistacia, and Rhus. DADSWELL & INGLE (1948) emphasized the high degree of correlation between the occurrence of these three (not always easily separable) types of parenchyma distribution and current tribal subdivision of the family. The groupings do, however, not exactly coincide. Similar findings were discussed by HEIMSCH (1942) who studied also exfra-Malesian genera and noted that there are only some trends for each tribe of the Anacardiaceae to show a particular wood anatomical feature more frequently than others. MOLL & JANSSONIUS' (1911) wood anatomical grouping of Javanese genera is probably artificial because it is based on too few genera, and because their interpretation of the fibre-type (with bordered pits) in Melanochyla, Semecarpus, and Spondias is questionable.

WILKINSON'S study (1971) has demonstrated the great diversity of leaf anatomical characters of considerable diagnostic and systematic significance. Only the main leaf anatomical characters can be mentioned here briefly. The trichomes in Anacardiaceae include simple unicellular or multicellular, uniseriate hairs (single or in groups); stalked, branched trichomes (the 'stellate hairs' of macromorphologists, in Lannea); peltate scales (in Campnosperma only) and a diversity of glandular hairs. These glands may be emergent or sunken, their stalks may be unicellular (as in the tribes Anacardieae, Semecarpeae and Rhoeae, except in Pentaspadon motleyi and Parishia maingayi) or multicellular (as in the Spondiadeae). The bodies of these hairs may be globose, ovoid, cylindrical or intermediate in shape. The adaxial epidermis contains glandular cells (probably mucilage cells) in the genera Buchanania and Campnosperma. Abaxial epidermal papillae of diverse but often highly characteristic morphology occur in many species of Drimycarpus, Melanochyla, Semecarpus, and Swintonia and in Rhus chinensis. DING HOU () made a key to the papillose genera and species based on appearance and distribution of the papillae at low magnification. The stomatal complex is predominantly cyclocytic in Anacardiaceae, but anomocytic stomata or anomocytic to cyclocytic stomata predominate in most genera of the Rhoeae and in Androtium and Swintonia p.p. Paracytic stomata characterize the genera Anacardium and Dracontomelon. The latter genus moreover shows columnar hydathode stomata. The stomatal complex in Buchanania and Spondias is rather variable and includes cyclocytic, anomocytic, paracytic and intermediate types. Columnar sclereids occur throughout the mesophyll in Bouea and in some species of Mangifera. The occurrence of secretory canals in the phloem of all Anacardiaceae is an outstanding feature. Such canals occur moreover in cortex and pith of a great number of genera and may also occur in the corresponding parts of petiole and midrib. The vascularization of midrib and petiole is fairly constant with a large, solid or disected, arc-shaped abaxial system and a flat adaxial plate. In some species of Lannea the adaxial plate is absent.

As with the wood anatomical diversity, there are trends for each tribe of Anacardiaceae to show a particular leaf anatomical character complex more frequently than others, but it is impossible to characterize each tribe unambiguously using leaf anatomical characters only. The reduction of Melanorrhoea to Gluta can be supported by anatomical evidence, although the absence of simple trichomes in Gluta renghas and G. velutina, and their presence in 4 species formerly referred to Melanorrhoea as reported by WILKINSON (1971) invites further studies to see whether the indumentum supports the recognition of at least two infrageneric taxa within Gluta s.l.

The entire evidence from wood and leaf anatomy unambiguously supports suggestions of affinities of Anacardiaceae with Burseraceae and Julianiaceae. — P. BAAS.

Taxonomy

In the latest monographic treatment of the Anacardiaceae LINDLEY () by ENGLER (), this family was divided into four tribes, i.e. Mangifereae, Spondieae, Rhoideae, and Semecarpeae. In 1892, ENGLER () added one more tribe, Dobi-neeae. His subdivision into tribes has, except for the additional tribe Dobineeae, generally been followed (cf. ).

In the position of the tribe Dobineeae ENGL., which consists of two extra-Malesian genera (both perennial herbs or subshrubs): Dobinea BUCH.-HAM. ex DON and Campylopetalum FOR-MAN, opinions differ. According to ERDTMAN (), pollen morphology is in favour of excluding Dobinea from the Anacardiaceae. FORMAN () considered, however, with good reasons, that these two genera for the present would be best placed in Anacardiaceae (tribe Dobineeae). This tribe has also been proposed as a separate family, Podoaceae BAILL. ex FRANCH. (corr. HUTCH.) by .

The Australian genus Blepharocarya F.v.M. has also been segregated from the Anacardiaceae as the type of a new family, Blepharocaryaceae, by AIRY SHAW (). The only character for this distinction is the concrescent, cupule-like axes of the ♀ inflorescence which seems insufficient for raising this genus to family rank. The coralloid inflorescence of the S. African genus Laurophyllus is morphologically halfway such contraction to a cupule-like structure.

Furthermore, the genus Pistacia has been proposed to represent a monotypic family, Pistacia-ceae (MARCH.) CARUEL (cf. ). It differs from other Anacardiaceae by a single perianth of which the segments are bract-like and are indeed by COPELAND Jr () suggested to be bracteal in nature, which would make the flowers apetalous. In addition KUPRIANOVA () stated that Pistacia would have a different pollen morphology although ERDTMAN l.c. had earlier advanced that pollen morphology supports that Julianiaceae should be referred to Anacardiaceae near Pistacia. From his detailed study of the reproductive structure of Pistacia chinensis COPELAND Jr concluded that many of its distinctive details are characteristic of Anacardiaceae and he added that also Julianiaceae agree in many details with this family. Also the gross morphology and the occurrence of resinous ducts make it reasonable to include Pistacia in Anacardiaceae, as was done by HUTCHINSON ( ).

In agreement with the subdivision by ENGLER, the main characters of each tribe occurring in Malesia with the Malesian genera belonging to it are given below. For the etymological spelling of the tribal names, I have followed that of .
  • Tribe Anacardieae — Mangifereae MARCH. Rév. Anacard. (1869) 185, excl. Solenocarpus W. & A.; ENGL. in DC. Mon. Phan. 4 (1883) 179; in E. & P. Nat. Pfl. Fam. 3, 5 (1892) 144. — Type genus: Anacardium L.
    Leaves simple, spiral or alternate (opposite in Bouea). Stamens 5-∞, in 1 or more whorls, sometimes 1-4 by abortion. Carpels solitary, or 5, free, with only one fertile (Buchanania & Androtium); style often lateral, gynobasic; ovule pendulous from a basal funicle. — (Buchanania, Androtium, Anacardium, Mangifera, Swintonia, Gluta, Bouea).
  • Tribe Spondiadeae DC. Prod. 2 (1825) 74 ('Spondiaceae'); ENGL. l.c. (1883) 175 & 242; l.c. (1892) 149. — Type genus: Spondias L.
    Leaves mostly compound, usually imparipinnate, trifoliolate, rarely simple (extra-Mal. sp.). Stamens twice the number of petals. Carpels united, mostly 5 or 4, sometimes more (Pleiogynium), or only 3, very rarely only 1; styles terminal; ovule pendulous from the apex of the locule. Fruits 3- to 5-celled, rarely more, or only 1-celled. — (Dracontomelon, Pleiogynium, Lannea, Spondias, Koordersiodendron, Pegid).
  • Tribe Semecarpeae MARCH. Rév. Anacard. (1869) 168; ENGL. l.c. (1883) 178; l.c. (1892) 174. — Type genus: Semecarpus L.
    Leaves simple. Stamens in one whorl, same number as the petals. Ovary consisting of (assumedly 3) united carpels, unilocular, usually partly immersed in and adnate to the fleshy, discoid, cupular or tubular disk; styles 3; ovule suspended from a funicle from the wall of the ovary above its middle or just below the apex. Fruit 1-seeded, usually with an enlarged, fleshy hypocarp. — (Melanochyla, Semecarpus, Drimycarpus).
  • Tribe Rhoeae MARCH. Rév. Anacard. (1869) 179 ('Rhoideae'); ENGL. l.c. (1883) 176; l.c. (1892) 154. — Type genus: Rhus L.
    Leaves usually imparipinnate, trifoliolate, or simple. Stamens in 1 or 2 whorls. Ovary consisting of 1 carpel or (assumedly 3) united carpels, 1-celled; styles 3 (2 or 1), terminal or lateral, free or united below; ovule attached on a short funicle from the base or suspended from the wall near the apex. Fruit 1-celled, in Campnosperma incompletely 2-celled by a pseudoseptum (2-celled in extra-Mal, genus). — (Pentaspadon, Campnosperma, Euroschinus, Rhus, Parishia, Pistacia).


Affinities of the family. Anacardiaceae sensu lat. is a coherent and natural family which is most closely allied to Burseraceae, especially expressed in the macromorphological characters as agreed by LEENHOUTS (), who already pointed out the similarities and differences between them. Besides, Anacardiaceae are assumed to be related in a greater or lesser degree to Sapindaceae, Meliaceae, Sabiaceae, Rutaceae, Simaroubaceae, Zygophyllaceae, Julianiaceae, etc.


Anacardiaceae can be distinguished from the related families by a combination of the following characters: (1) leaves exstipulate; (2) presence of resin-ducts with resinous sap usually quickly turning black when exposed to the air; (3) usual presence of a distinct disk; (4) ovary usually 1-celled and with only 1 ovule; (5) ovule apotropous; (6) drupaceous fruits; (7) seeds usually exalbuminous.

Cytology

Chromosome numbers of about 50 species belonging to about 17 genera were reported with somatic numbers: 2n = 24, 28, 30, 32, 40, 48, 60, which clearly points to the occurrence of polyploidy. Of the following genera, which have their representatives (including cultivated ones) in Malesia, chromosome numbers have been recorded: Anacardium (2n = 40), Lannea (2n = 28, 30, 40), Mangifera (2n = 40), Pistacia (2n = 24, 28, 30), Rhus (incl. Toxicodendron) (2n = 30, once reported as 2n = 32), Semecarpus (2n = 60), and Spondias (2n = 32). In view of the economic importance of mango (Mangifera indica) it would be highly desirable to obtain information on chromosomes of the (indigenous) species from Malesia. Taking the family as a whole, more information on chromosomes is needed, especially for those taxa found in Indo-Malesia. The chemical characters of Anacardiaceae were discussed more than 10 years ago in my 'Chemotaxonomie der Pflanzen' ().

The family yields many valuable products. Examples are: (a) important tanning materials such as sumac (= sumach = dried and ground leaves of several species of Rhus), quebracho (= heartwood extracts of species of Schinopsis) and Chinese galls (= very tannin-rich galls of Rhus chinensis MILL., syn. R. semialata MURR.); (b) mastic (an oleoresin obtained from Pistacia lentiscus L.; (c) the varnish producing latices of a number of so-called lacquer trees (e.g. Rhus verniciflua STOKES, syn. R. vernicifera DC.; and Gluta usitata (WALL.) DING HOU, syn. Melanorrhoea usitata WALL.); (d) cashew nut shell liquid from Anacardium occidentale L. which is used for the manufacture of plastic resins; (e) tropical fruits such as mango (Mangifera indica L.), hog-plum (Spondias spp.) and cashew apple (Anacardium occidentale L.); (f) edible seed kernels like cashew nuts (Anacardium occidentale L.) and pistachio nuts (Pistacia vera L.); (g) woods used for furniture and other purposes (e.g. species of Campnosperma, Dracontomelon, Gluta, Koordersiodendron., Swintonia). Phytochemical research was much stimulated by the manifold uses of members of the family and by the severe allergenic skin disease caused by species like poison ivy (Rhus radicans L.), poison sumac (Rhus vernix L.), poison oak (Rhus diversiloba TORR. & GRAY) and poison wood (Metopium toxiferum (L.) KRUG & URBAN), and various trees of several genera in Malesia known by the vernacular name rengas.

Formerly (1964) Anacardiaceae were chemically characterized as follows: (1) There is a strong tendency to deposit silicic acid in leaves, especially in Mangifereae and Spondiadeae. (2) The contents of the secretory canals occurring in the phloem of all species represent an outstanding feature; depending upon the taxa, these canals store mainly oleoresins (= essential oils + triter-penic resins; e.g. mastic) or latices containing mucilages, phenol oxidases (= laccases) and alkylated phenols. The technical and toxic properties of these latices are mainly governed by structural details of the predominating phenolic constituents; the strongly allergenic urushiols of the Japanese lacquer trees and of poison ivy are alkylated o-dihydroxyphenols. (3) There is a strong tendency to accumulate gallitannins in leaves, galls and barks and condensed tannins in heartwoods. (4) There is a tendency to produce 5-desoxyflavonoids (e.g. leucofisetinidine, fustin, fisetin, sulphuretin, robinetin, dihydrorobinetin) in heartwoods. (5) The flavonols kaempferol, puercetin and myricetin and the proanthocyanidins (formerly called leucoanthocyanidins) brocyanidin and prodelphinidin are common phenolics of leaves; the compounds with a tri-hydroxylated B-ring (myricetin, prodelphinidin), however, are possibly restricted to Rhoeae. (6) Leaf juices of Anacardiaceae are very acid; quinic acid (mainly in young leaves) and shikimic acid contribute in a high degree to the acidity of the cell saps.

Recent phytochemical research added much to our knowledge of the chemistry of several tannins, of the triterpenic resins (Mangifera indica L., several species of Pistacia, Schinus terebin-thifolius RADDI) and of mucilages (Anacardium occidentale L., species of Lannea and Loxoptery-gium, Mangifera indica L., latex of Japanese lacquer trees). M. GROSS C.S. () analyzed very carefully the urushiol fractions of several toxic American Anacardiaceae; they are mixtures of o-diphenolic compounds with straight C15 or C17 lateral chains; the compounds with di- to tetraenoic alkyle residues are much more toxic than those with saturated or mono-unsaturated lateral chains.

Totally new chemical constituents of Anacardiaceae are alkaloids and biflavonoids. S. R. JOHNS c.s. () isolated an indolic alkaloid from the leaves of Draconto-melon dao (BLANCO) MERR. & ROLFE (syn. D. mangiferum Bl.) and suggested that it is biogeneti-cally related to canthinone and related rutaceous alkaloids. Biflavanones (e.g. rhusflavanone, succedaneaflavanone) and biflavones (e.g. agathisflavone, amentoflavone, hinokiflavone and robustaflavone) have been isolated from fruits and seeds of Rhus succedanea L. () and Semecarpus anacardium L.f. (). Biflavonoids were formerly considered to be characteristic of Gymnosperms but were detected later in some Anacardiaceae, Euphorbiaceae, Guttiferae and in the genus Viburnum; hence they seem to be much more wide-spread than it was originally presumed.

Concluding it may be stated that much has been contributed since 1964 to our knowledge of the chemical characters of anacardiaceous plants. The detection of an indolic alkaloid and of biflavonoids implies that really new biochemical trends of Anacardiaceae became known in recent time. This does not add much to our understanding of the true affinities of the family, however, because all the presently known striking biochemical features of Anacardiaceae (hydro-lizable and condensed tannins, triterpenoid resins, alkenylated phenols, 5-desoxyflavonoids, biflavonoids and canthinone-like indolic alkaloids) doubtlessly evolved more than once within Angiosperms. For tracing phylogenetic relationships between taxa of family rank and higher ranks such characters are of little value unless all facts needed for an unambiguous interpretation of their systematic meaning are available; this is not yet the case with the chemical characters of Anacardiaceae. — R. HEGNAUER.

Uses

Anacardiaceae produce some of the best known, economically important, tropical fruits, nuts and other products. For more detailed information, readers should consult the following publications: .

Fruits and nuts. The renowned Mangifera indica (mango), Spondias cytherea (hog-plum) and Anacardium occidentale (cashew-nut) are widely cultivated in the tropics. Pistacia vera L. (pistachio nut or green almond) is grown in the Mediterranean region, especially in Sicily. There are also others cultivated locally in Malesia for their edible fruits: Mangifera caesia, M. foetida, and M. odorata; Spondiaspinnata and S. purpurea; Bouea macrophylla, and Dracontomelon spp.

Timber. In Malesia some species of Dracontomelon, Swintonia, Gluta, Buchanania, Campno-sperma, and Koordersiodendron can grow into big trees. The heartwood of some of these species is hard, durable, excellent for furniture, building, etc. Planks or boards of these timbers have irregular, beautiful, black markings. It is desirable and urgently needed to do research to find some means to remove the irritant sap, so one can safely handle and use these valuable timbers. Cf. .

Lacquers. The Oriental lacquer is economically important in China and Japan; it is a natural product obtained from the resinous sap of Rhus verniciflua STOKES and R. succedanea. The Burmese lacquer is the product of Gluta usitata (WALL.) DING HOU (syn. Melanorrhoea usitata WALL.).

Tannins. The South Americans pecies of Schinopsis, especially S. quebracho-colorado (SCHLECHT.) BARKLEY & MEYER is one of the world's most important sources of tannin (cf. ). Tannins are also obtained from some members of Rhus: R. coriaria L. (Sicilian sumac); R. glabra L., R. typhina L. and R. copallina L. (American sumac); and R. chinensis (using the nut-galls).

Other minor uses. There are some further miscellaneous uses of bark, leaves, flowers, kernels, etc. which are in local use as medicine, vegetable, food, etc. There are also some other economic products (oils, dyes, varnishes, gums, etc.) which are used only on a limited scale and for local consumption. See for these under the species.

Dermatitis. Anacardiaceae have usually secretory ducts in both vegetative and reproductive parts. The resinous liquid substance is colourless or pale yellow and clear, more rarely thick and greyish brown, hardening and turning black when exposed to the air. , . In some species this resinous sap is mild and causes only a slight itching of the skin on contact, but in others the irritant sap is of a powerfully caustic nature and blisters the skin. The poisonous quality varies with the species. The susceptibility to such resinous sap varies according to the sensitivity of the person involved. Even eating mango fruit may cause mild skin-itching in very susceptible persons.

In the temperate zone the poisonous qualities are best known from species of Rhus in North America, the so-called poison ivies and poison oaks. Also in Malesia Rhus spp. may contain poisonous qualities, e.g. R. succedanea.

Similarly or even more dangerous trees are found in the Malesian tropics where they are known under the collective name rengas; they belong to the following genera: Gluta (incl. Melanorrhoea), Melanochyla, Semecarpus, and Swintonia. See discussion by .

The poisonous constituent of the resinous sap is volatile and will gradually disappear. For this reason timber of rengas trees must be dried and exposed for several years as it is otherwise dangerous to handle. Lacquered articles or furniture made from dried timber just mentioned may be still toxic to persons who are especially susceptible (cf. ).

In the lowland forests in Malesia rengas trees are common and it is important that one should be able to recognize such trees. It is undesirable to shelter under a rengas tree during a tropical shower, because raindrops may carry the poison from the leaves (cf. ). CORNER commented on recognition of rengas trees in the field "that the inner bark of all rengas trees is bright pinkish or reddish brown, in contrast with the white sapwood; and on the surface of the trunk and the limbs there are nearly always a few black stains where the sap has oozed out and darkened. These stains are the surest guide to the recognition of the trees. Black lines may also be seen in the freshly cut sapwood or just beneath the bark and, if the bark has been extensively injured some hours or days previously, the wound will be covered with a pitch-black smear. In a few species the sap darkens quickly but in most it takes about half an hour." CORNER added that "it is doubtful whether animals suffer from the poison; monkeys and squirrels appear to be immune, for they will eat the rengas fruits; and certain kinds of insects feed on sap, their bodies becoming lacquered."

RIDLEY () quoted from a report that once two whole companies of a military expedition were affected by serious injuries to the feet caused by wading across rivers which had fallen rengas fruits in the water.

The volatile poisonous substance, a hitherto unidentified aromatic compound, may be conveyed to some distance by the smoke and flakes of burning material, or by saw dust, of the Anacardiaceae. The fumes arising from the roasting cashew-nuts are very irritating (cf. ). It has occurred that inhaling smoke around camp-fires of careless wood-cutters in Borneo had fatal results; this is fortunately rare as native peoples are usually aware of the danger involved with rengas trees.

I witnessed victims of rengas poisoning during my field trip on Anacardiaceae to Malesia and Singapore in 1966. One collector, who chopped down a tree (c. 15 m tall) of Semecarpus bunburyanus on Mt Kinabalu for obtaining fruiting material, and another, who in Malaya climbed a low-branched tree of Swintonia spicifera to collect specimens, had painful effects of itching, or a swollen face, ears and eyes. I was with them there preparing the collections; fortunately, I was not affected.

A surveyor of a timber company in Sarawak had inflamed arms and legs and suffered painful itching when he came back from his work in the forest. It was found that he wore short-sleeved shirt and shorts, and incidentally had touched the wet leaves of young Melanochyla plants.

In Malaya, I met persons who said that they would not be affected by the rengas sap. One labourer was felling a (big) tree of Gluta wallichii; he posed for a photograph to show that he was immune ().

The remedy for the sap-poison is to apply weak solutions of mild alkali or active reducing agents, such as formalin, sulphites, 'hypo', or 'potash' (), or using antihistamine tablets or injections followed by medical advice (). If one has severe reaction on contact with the poisonous plants, it is advisable to see a doctor.

Mr. ANTA, one of the excellent Indonesian professional collectors of Herbarium Bogoriense severely suffered from rengas poisoning on hands and arms when returning from an expedition to New Guinea. At the advice of the dermatologist Professor VERBUNT, at Djakarta, he was efficiently cured by bathing his blistered hands in a weak solution of tannin (crystals of which can be had cheaply from any druggist) for some 5-10 minutes each day and later less frequently. Mr. ANTA experienced also that new outbreaks could be expected after many months (even a year), but could be immediately suppressed in this way; on later expeditions he always carried tannin crystals in his outfit (comm. VAN STEENIS).