Chrysobalanaceae

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Chrysobalanaceae

Description

Trees or shrubs (or rarely suffrutices outside Malesia). Leaves simple, alternate, often coriaceous, glabrous or with an indumentum on undersurface, margin entire; Stipules 2, minute and caducous to large and persistent, usually linear-lanceolate. Inflorescence racemose, paniculate or cymose; Flowers actinomorphic to zygomorphic, hermaphrodite or rarely polygamous, markedly perigynous. Petals 5 (absent in some Neotropical species), inserted on margin of disk, commonly unequal, imbricate, deciduous, rarely clawed. Stamens indefinite, 2-60 (to 300 in Neotropics), inserted on margin of the disk, in a complete circle or unilateral, all fertile or some without anthers and often reduced to small tooth-like staminodes; Ovary basically of three carpels but usually with only one developed, the other two aborted or vestigial, variously attached to (the base, middle or mouth of) receptacle, usually sessile or with short gynophore, pubescent or villous; Ovules erect, with micropyle at base (epitropous). Fruit a fleshy or dry drupe of varied size, interior often densely hairy; Seed erect, exalbuminous, the testa membraneous;

Distribution

Africa: present Asia: present Asia-Tropical: Pacific: present, Fiji (Fiji) Pantropical: present South America: present neotropics: present
Pantropical with 456 species in 17 genera; 365 species in the Neotropics, 57 in Africa, and 34 in Asia, Malesia and the Pacific.
Seven genera are native to the Flora Malesiana region and one species of an eighth genus, Chrysobalanus, from Africa and South America, has naturalized in Malesia and Fiji and is therefore included in this treatment. All four tribes of Chrysobalanaceae are represented in the region. The genera treated here fall into the following tribes of PRANCE & WHITE:
  • Tribe Chrysobalaneae: Chrysobalanus, Licania, Parastemon.
  • Tribe Parinarieae: Hunga, Parinari.
  • Tribe Couepieae: Maranthes.
  • Tribe Hirtelleae: Atuna, Kostermanthus.


The genera Atuna, Hunga, Kostermanthus, and Parastemon are confined to the Malesian and Pacific region. Licania is predominantly a Neotropical genus (186 species there) with a single species in West Africa and three in Malesia. Parinari is a pantropical genus with almost equal representation in all three major regions of the tropics, and Maranthes is predominantly an African genus with one abundant and widespread species in Malesia and the Pacific and a single closely related species in Central America.

Dispersal

The fruits of Chrysobalanaceae are very uniform in basic structure but remarkably diverse in functional detail. Despite their uniformity they have become adapted to a wide range of dispersal agents, sometimes within a single genus or species; however, few species have been studied in the field.

Chrysobalanus icaco subsp. icaco is dispersed by ocean currents, and also by bats, rodents and monkeys, and possibly by birds; C. cuspidatus is said to be dispersed by birds.

Some Neotropical species of Licania are bat-dispersed, whereas the fruits of several South American riverine species float and are also eaten by fish; those of the African species L. elaeosperma are also transported by water. The Malesian species L. splendens is dispersed by the fruit pigeon Ducula aenea.

Various species of Parinari are known to be dispersed by bats, elephants, baboons and other primates, a scatter-hoarding squirrel, fruit pigeons, rheas, emus, agoutis and fish. Species of Couepia, Licania and Parinari are frequently eaten by bats in the Neotropics.

Maranthes corymbosa is dispersed by birds, most notable hornbills and fruit pigeons, and, at least for short distances, by a scatter-hoarding squirrel. The fruits of some African species are eaten by monkeys which are possibly mainly destructive.

A tuna is dispersed by ocean currents and a scatter-hoarding squirrel and possibly by wild pigs.

Morphology

All species of Chrysobalanaceae are woody and most are trees or treelets. All are leptocaul. Several, including species of Atuna, Kostermanthus, Licania (Neotropical), Magnistipula (African), Maranthes and Parinari, exceed a height of 30 m and are important constituents of the upper forest canopy or are émergents. Six African and Neotropical species belonging to Licania, Magnistipula and Parinari are geoxylic suffrutices with massive woody underground parts, but rather exiguous aerial shoots which are capable of only limited upward growth and a similar form occurs in Parinari nonda in Australia.

In their architecture and growth-dynamics those Chrysobalanaceae that have been studied exhibit the model of TROLL. This has been demonstrated only in African and Neotropical species.

Herbarium specimens of Atuna show a distinct pattern of branching which is difficult to describe except in terms of development based on the living plant.

Buttresses are normally absent but frequently well-developed in some species of Parinari and Atuna, for example, P. canarioides, P. costata, P. oblongifolia, A. cordata and A. excelsa, and the trunk of some species of Parinari, e.g. P. parva and P. gigantea is often fluted at the base.

The leaves, which are simple and spirally inserted, are frequently arranged distichously. Most species have stiff, coriaceous, evergreen leaves which contain abundant silica inclusions.

Stipules are nearly always present but are sometimes small and caducous. In some Neotropical species of Parinari the stipules reach a length of 7 cm, they are up to 4 cm in Parinari parva. In Atuna they are prominently keeled, a unique feature in the family.

The lamina is entire, in all Malesian species. In nearly all species of Parinari, and a few Neotropical species of Licania, the veins on the lower surface are extremely prominent and form a dense network occupying more than half of the leaf surface so that the stomata are confined to relatively small sunken crypts which are densely filled with short curly hairs.

Foliar glands occur in most, possibly all, species. They secrete nectar which is eaten by ants, and function chiefly on young leaves. On mature leaves of herbarium specimens they are not always clearly visible. The structure and distribution on the leaf of the glands varies greatly from genus to genus and provides characters of considerable taxonomic importance. Small discoid glands occur in various places on the lower surface or margins of the lamina in Parastemon. There are larger, sometimes ill-defined, glandular areas towards the base of the lamina in Maranthes. In Parinari conspicuous glands occur on the petiole.

The inflorescence is very variable. In Chrysobalanus the few-flowered inflorescence is a short raceme of cymules or is cymose throughout, or is a false raceme or a subsessile fascicle. In Parastemon the inflorescence is a simple or branched raceme. Hunga and Malesian species of Licania have simple or branched racemes of usually congested cymules. More complex mixed inflorescences with cymose ultimate units are found in Kostermanthus and Parinari, and the inflorescence of Maranthes is corymbose.

Since the inflorescence is usually cymose, at least in part, a distinction between bract and bracteole cannot always be drawn. Bracts and bracteoles are usually small but in nearly all species of Parinari they are relatively large and enclose small groups of developing flowers.

In most species the flowers appear to be bisexual, but future field work may show that this is not always so. Parastemon urophyllus is said to be polygamodioecious.

Floral symmetry varies from almost completely actinomorphic, apart from the lateral style, in Chrysobalanus, Parastemon, and most species of Licania to strongly zygomorphic in Kostermanthus. Actinomorphic flowers are patelliform or shallowly cupuliform, and zygomorphic flowers usually have a long receptacle-tube, but in Kostermanthus the strongly zygomorphic flowers have a very short receptacle. In the Chrysobalanaceae the receptacle-surface is always lined with nectar- secreting tissue, which sometimes, as in Maranthes corymbosa, almost completely fills the tube. In most genera the entrance to the receptacle tube is blocked by long straight retrorse hairs, but these are lacking in Kostermanthus. In Parastemon the nectariferous lining of the receptacle is freely exposed.

There are always five, completely free, slightly to strongly imbricate sepals which vary from subequal in Chrysobalanus to markedly unequal in Kostermanthus. In most genera they are acute or subacute but in Kostermanthus and Maranthes they are suborbicular and deeply concave. Petals are present in all Malesian species but absent in many Neotropical species of Licania. There are always five. They are mostly caducous. In shape they vary from linear-spathulate (Chrysobalanus) to orbicular. They are usually subequal, but in Kostermanthus they are very un- equal in shape and size and are strongly unguiculate.

Stamens vary in number from two in Parastemon urophyllus to 40 in Maranthes. In Chrysobalanus, most species of Licania, Parastemon versteeghii, and Maranthes they form a complete or almost complete circle round the entrance to the flower and all or most are fertile. Otherwise the fertile stamens are inserted unilaterally opposite the carpel. Staminodes are frequently present opposite the style. In several genera the filaments appear to be united at the base, but it is sometimes difficult to decide whether this represents true union or whether the filaments are free but inserted on a development of a receptacular rim. In Maranthes the stamens are inserted in two or more rows on the outer surface of what appears to be a receptacular annulus. In length the filaments vary from much shorter than the calyx, as in Hunga, Parastemon and some species of Licania, to very much longer in Maranthes. In Kostermanthus the filaments are united for at least half of their length to form a conspicuous ligule.

The gynoecium fundamentally is composed of three carpels which are free except for the gynobasic style. In most species there is only one functional carpel, though one or two small rudimentary carpels can sometimes be seen. Due to the development of a false dissepiment the ovary is bilocular in Hunga, Parinari, and Atuna.

The fruit is basically a drupe but there is considerable variation in detail, apparently associated with dispersal and germination. In Chrysobalanus, Parastemon and Hunga the endocarp has a smooth surface and is sharply differentiated from the mesocarp. In the other genera the differentiation is less well-defined. In Chrysobalanus and Hunga, seedling escape is effected by means of longitudinal lines of weakness. In Parastemon and Maranthes two large lateral plates fall away permitting the seedling to emerge. In Parinari there are two small basal 'plugs' or obturators. All other genera seem to lack specialized means of seedlings escape.

In Chrysobalanus, Licania, Parastemon, Parinari, and Atuna, germination is cryptocotylar, whereas in Maranthes it is phanerocotylar.

Anatomy

— Leaf anatomy. Indumentum, if present, consisting of long unicellular hairs. Variously positioned glands (extrafloral nectaries) with slender upright epidermal secretory cells commonly present. Wax present as platelets (FEHRENBACH & BARTHLOTT, 1988). Stomata mostly paracytic, confined to the lower leaf surface. Upper epidermis often composed of tall cells; with mucilaginous inner walls in some species. Hypodermis often present. Mesophyll entirely composed of palisade-like cells, more rarely dorsiventral and differentiated into palisade and spongy tissue. Asterosclereids occasionally present in mesophyll. Veins mostly with sclerenchyma sheaths including sclereids with U-shaped wall thickenings, sometimes vertically transcurrent. Midrib and distal end of petiole with a closed vascular cylinder, with or without additional adaxial or medullary collateral bundles. Silica bodies and silicified cell walls common, especially in epidermis.

Young stem. Cork arising superficially. Pericyclic sclerenchyma ring composed of fibres and sclereids with U-shaped wall thickenings. Secondary phloem occasionally with secretory (tannin?) cells. Sieve tube plastids of the S-type (BEHNKE, 1984). Silica bodies often present in pericycle, phloem and xylem rays, and in pith.

Wood anatomy. Growth rings absent or, if present, defined by differences in the spacing of tangential parenchyma bands. Vessels diffuse, often in a weakly oblique pattern, (almost) exclusively solitary, tending to be of two distinct sizes, the larger ones very wide (200-300 µm). Vessel perforations simple. Tyloses often present in heartwood, sclerotic in some species. Vessel-ray pitting including elongate horizontal or oblique to almost vertical pits with strongly reduced borders, often unilaterally compound. Fibres often thick-walled, with distinctly bordered pits throughout the tangential walls, and in the radial walls often confined to fibre-ray contacts (fibre-tracheids); in contact with vessels often less thick-walled and with biseriate bordered pits (= vasicentric tracheids). Parenchyma in fine uniseriate or locally bi(-tri)-seriate, regular or irregular wavy tangential bands. Parenchyma strands typically long, of up to 16 cells. Some axial parenchyma cells with spiral thickenings in A tuna p.p., Licania, Maranthes p.p., and Kostermanthus (TER WELLE, 1975). Rays predominantly uniseriate, but in some taxa also biseriate, typically weakly heterogeneous with (often weakly) procumbent central cells and one row of square to upright marginal cells (Kribs type III), sometimes homogeneous and composed of procumbent cells only. Silica bodies universally present in ray cells, more rarely in axial parenchyma cells. Rhomboidal crystals in chambered axial parenchyma cells noted in Parastemon.

Taxonomic notes based on vegetative anatomy. The above general anatomical description is based on the literature (for leaf and young stem anatomy mainly KÜSTER, 1897, as abstracted by SOLEREDER, 1899; and PRANCE, 1972, and PRANCE & WHITE, 1988, for wood anatomy from many sources), amplified with original observations on slides present in the Rijksherbarium at Leiden. A number of anatomical characters may prove to be of considerable taxonomic significance at the genus or species level (mucilaginous leaf epidermis, distribution of silica grains in leaves, young stem, and wood, vascular pattern and sclerenchyma support of leaf veins and petiole, fibre and sclereid distribution pattern of the mature bark (ROTH, 1981), spiral thickenings in axial parenchyma cells of the wood, ray width and histology, etc.). However, for the Malesian Chrysobalanaceae their diagnostic value remains largely untested. On the whole the Chrysobalanaceae are anatomically rather homogeneous, and as repeatedly emphasized, quite distinct from the Rosaceae. Anatomically Chrysobalanaceae are also distinct from the numerous families to which they have been compared in the search for closest relatives.
— P. BAAS.

Taxonomy

An extensive review of the generic limits of the family has been published: . This contains full details of taxonomic history, morphology, anatomy, pollen, ecology and distribution of the family. A condensed version of these subjects is given here. Details of the Neotropical members of the family are given in: . The African members of the family were treated in: .

Uses

Members of the Chrysobalanaceae are used by the local people everywhere, for building, fuel, charcoal and in folk medicine. The fruits and seeds of some species are highly esteemed, and others are eaten in times of scarcity; some are used in the preparation of alcoholic beverages. At present, Chrysobalanaceae are only of local importance commercially, but, with improved communications and technology, their potential as a source of construction timber, fruits, and edible and industrial oils appears to be promising.

The Malesian standard timber name for various genera of Chrysobalanaceae is merbatu.

Edible fruits and seeds. Chrysobalanus icaco is tinned and bottled in syrup and sold in Colombia and Venezuela under the name Icacos. The fruit of several Neotropical species of Couepia and Parinari are eaten. In Amboina a dish called Koku koku is prepared from the mashed seeds of A tuna excelsa mixed with raw or fried small fish, ginger, onions, chillies and lime juice.

Wood. Despite the large supplies of Chrysobalanaceae wood potentially available, commercial sawn timber is produced only in relatively small amounts. This is because its high silica content blunts even tungsten-tipped saws. Because the wood of many species is resistant to marine borers, it is used throughout the tropics for piers and other marine constructions.

Caulking and waterproofing agent. In the Solomon Islands the principal use of A tuna excelsa sensu lato is for caulking the seams of plank-built canoes. The seeds, which are known as 'putty nut' are pounded to a putty-like consistency. After application the putty hardens and darkens, but if exposed too long to the sun it cracks, so canoes drawn up on the beach are often kept in the shade of sheds. In the central and south-eastern Solomons it is used for setting shell inlay in wood bowls, figures and other articles. The north-western Solomon Islanders also use it for waterproofing bottles made from gourds. In the Admiralty Islands (Manus) coiled baskets are coated with it to make them waterproof (B.A.L. CRANSTONE, in litt., 14 June 1983).

History of Parinari. The taxonomic history of Parinari is complex. At least some species of all Malesian genera except Chrysobalanus, and Parastemon have at one time or another been placed in Parinari.

All species of Atuna and Maranthes have been included in Parinari. Despite their considerable differences from Parinari sensu stricto in virtually all other respects, these genera have one feature in common — a bilocular ovary. It was the adoption of this character as a generic criterion, especially by BENTHAM (1849), that led to the increasingly artificial nature of Parinari. As Parinari became more and more heterogeneous even some species with unilocular ovaries were included, for example, the species now placed in Kostermanthus.

In the original description of Parinari, which was based on P. campestris and P. montana from French Guiana, AUBLET (1775) mentioned the bilocular ovary, but he does not appear to have attached much importance to it.

DE JUSSIEU (1789), who brought all previously described genera of Chrysobalanaceae together for the first time, knew some of them only from the original descriptions and illustrations. His implication that Parinari differs from the other genera principally in its bilocular ovary seems to have laid the foundations for the subsequent confused history of the group.

DE JUSSIEU was the first to extend the concept of Parinari to another continent by citing in synonymy two manuscript names of AD AN SON from Senegal, Mampata and Neou. The former was subsequently described as P. excelsa and the latter as P. macrophylla by SABINE.

The following year, in his Prodromus, DE CANDOLLE (1825), who only knew the four species mentioned above, divided Parinari into two sections. Section Petrocarya (correctly section Parinari) was based on a superfluous generic name which SCHREBER (1789) substituted for the earlier Parinari. It included AUBLET's original species. Section Neocarya was based on P. senegalensis DC. [now Neocarya macrophylla (SABINE) PRANCE], but P. excelsa was associated with it, probably because its type-description is inadequate to characterize it properly. Parinari macrophylla is not mentioned by DE CANDOLLE. He was also apparently unaware of the first true Parinari to be described from Asia, P. sumatrana BENTH., which had been described by JACK in the illegitimate genus Petrocarya in 1822. DE CANDOLLE indirectly emphasized the importance of the bilocular ovary of Parinari by describing the ovary of all other genera as unilocular.

During the first half of the nineteenth century, in addition to Neocarya macrophylla, a few other species, which belong to other genera, were described in Parinari or its illegitimate synonym Petrocarya, because of their bilocular ovary. Thus JACK (1822) described Petrocarya excelsa (now A tuna excelsa), and BENTHAM (1840) published Parinari coriacea (now Exellodendron coriacea), but it was BENTHAM'S treatment of Parinari in HOOKER'S Niger Flora (1849) that firmly established Parinari as an artificial genus.

Whereas earlier workers had implied that the bilocular ovary is a diagnostic character of Parinari, BENTHAM referred to the spurious dissepiment which separates the ovules as 'the essential character.' BENTHAM divided Parinari into three sections as follows:
  • Section 1: Petrocarya (correctly Parinari) included the African species P. excelsa and P. curatellifolia, all the known American species including P. coriacea (now Exellodendron coriaceum), and, with some doubt, three species BENTHAM had not seen himself, namely P. sumatrana BENTH. (a true Parinari), P. glaberrima HASSK. (now A tuna excelsa) and P. scabra HASSK. (now A tuna scabra).
  • Section 2: Sarcostegia BENTH. included two new species, P. polyandra (now Maranthes polyan-dra) and P. griff it hiana (now Maranthes corymbosa), and, with some doubt, also P. jackiana BENTH. (based on Petrocarya excelsa, now Atuna excelsa) which BENTHAM had not examined.
  • Section 3: Neocarya DC. contained P. macrophylla (now Neocarya macrophylla) and its synonym P. senegalensis.


BENTHAM'S circumscription of Parinari was probably much wider than he imagined, largely because of the inclusion of the Asian species he only knew from the literature. He appears to have adopted it with some reservation. Parinari polyandra has c. 40 fertile stamens and BENTHAM mentions that this, in conjunction with the glandular leaves and fleshy 'calyx', might 'suggest the establishment of a distinct genus.' He clearly believed that the stamen number of Parinari varies more or less continuously, but the evidence he cites is partly on the species he had not studied.

BENTHAM'S circumscription of Parinari included five genera which are now regarded as distinct, namely, in additon to Parinari itself, A. tuna RAFIN., Exellodendron PRANCE, Maranthes BLUME and Neocarya PRANCE. TWO of these from Malesia had enjoyed a brief period of generic recognition. Thus, Maranthes was described by BLUME in 1825, but three years later he transferred the type species to his illegitimate Exitelea. Atuna was described by RAFINESQUE in 1838, but remained disregarded for more than 100 years, though one of its species was independently described by HASSKARL in 1842 as the type of his new genus Cyclandrophora. It appears that HASSKARL had little faith in his new genus for he united it with Parinari within a year of its publication, although it has little in common with the latter, other than the bilocular ovary.

Since BENTHAM (1849) nearly all species of Chrysobalanaceae with false dissepiment (and even some without) were automatically placed in Parinari regardless of any other consideration.

As new species now placed in Exellodendron, Maranthes and Atuna were described they were all placed in Parinari. Likewise, equally disparate elements which are now placed in Bafodeya PRANCE, Hunga PANCHER ex PRANCE and Kostermanthus PRANCE joined the assemblage.

Phytochemo

Chemical knowledge about the family Chrysobalanaceae is still scanty. HEGNAUER (1973) treated it as Chrysobalanoideae sub Rosaceae. Chrysobalanaceae are noteworthy for their tendency to accumulate silica (SiO2) in leaves and in the wood where usually every ray cell contains one globular silica inclusion. Leaf flavonoid patterns are dominated by the flavonols quercetin and kaempferol; some taxa also have myricetin. Proanthocyanidins (formerly called leucoanthocyanidins), i.e. condensed tannins, were demonstrated to be present in leaves of few species of Chrysobalanusy Licania, and Parinari, but galli- and ellagitannins have not yet been traced in the family. The recent flavonoid investigation of 21 species of Parinari (CORADIN, GIANNASI & PRANCE, 1985) resulted in the identification of a number of 3-glycosides of kaempferol, quercetin and myricetin, and showed restriction of myricetin glycosides to four African species; dihydroquercetin('taxifolin')-3-glycosides were noticeable only in Asian Parinari insularum from the Pacific islands and vicenin-like C-glycoflavones only in a few African populations of P. excelsa. Myricetin was also observed in leaves of Licania macrophylla which besides has much condensed tannins in all parts, saponins in leaf, pericarp, seed, and stem and root bark; alkaloids in stem and root bark (GRENAND, MORETTI & JACQUEMIN, 1987). Cyanogenic glycosides which are characteristic of a number of Rosaceous taxa have not been traced in Chrysobalanaceae hitherto. The most noteworthy chemical character known from the family at present is the fatty acid pattern of their seed triglycerides; conjugated trienoic and tetraenoic Cig-acids such as alpha-elaeostearic and parinaric acids are present as major fatty acids in seed oils of species of Chrysobalanus, Licania, and Parinari s.l. (i.e. including Atuna, Maranthes and the African Neocarya).

This character, however, which links Chrysobalanaceae biochemically with Prunoideae (same type of seed oils in some Prunus s. I. species) seems not to be universal in the family. According to JONES & EARLE (1966) seed kernels of a species of Couepia (Central & South America) contained an oil without conjugated unsaturation. Still too little is known from the chemistry of this taxon to allow a sound chemotaxonomic discussion.
— R. HEGNAUER.