Sapindaceae

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Sapindaceae

Description

Trees, shrubs or lianas, rarely herbaceous climbers; Leaves spirally arranged, rarely opposite or whorled, simple, biternate, digitate or (bi)pinnate; Almost always spirally arranged, rarely opposite or whorled, usually pari- or imparipinnate, sometimes digitate, unifoliolate, or simple; if paripinnate often the rachis ending in an acumen. Stipules present in only a few genera (e.g. Cardiospermum); more often pseudo-stipules present: lowermost pair(s) of leaflets at the very base of the petiole, much smaller than and usually of a different shape as the other leaflets (e.g. Alectryon repandodentata, Lepisanthes subg. Otophora, Pometia). See Weberling & Leenhouts 1966; Weberling 1976.
Axillary and often several together, pseudoterminal (terminal vegetative bud present), or terminal, or rami- or cauliflorous; often more or less thyrsoid or paniculate; cymes (cymules) one- to many-flowered, either dichasia, cincinni, or bos-try xes, various reductions may obscure their true form, however.
Inflorescences axillary, often together pseudoterminal, terminal or ramiflorous, thyrsoid, with or without branches; Flowers usually unisexual, rarely bisexual, actinomorphic or zygomorphic. Usually 4- or 5-merous, actinomorphic to strongly zygomorphic. Sepals entirely free, outer one or two much smaller than the inner three, and in bud imbricate (e.g. Cupaniopsis, Guioa, Lepisanthes) to highly connate, all equal and in bud apert (Cu-bilia, Litchi). Petals free, with or without a claw, often the inside with 1 or 2 scales or auricles (inrolled margins), especially in the latter case the petals obliquely funnel-shaped ('peltaten Kronblatter', Leinfellner 1958); the scales may be provided with crests (e.g. Guioa, Sarcopteryx, Toechima) or not. Disc complete or interrupted, annular or saucer-like to semi-annular. Ovary 1-, 2-, or 3-celled, style shorter to longer than the ovary, stigma short or long, erect or recurved and lobed, or closed and with lines of stigmatic papillae on the outside.
Sepals 4 or 5, rarely more, free to almost totally connate, equal to distinctly unequal, and then the outer 1 or 2 much smaller than the inner three, herbaceous to petaloid, in bud imbricate, valvate or apert. Petals absent or 2-6, free, usually clawed, often with 1 or 2 scales or auricles (= inrolled margins), scales crested or not. Stamens 5-10(-74), usually 8, nearly always inserted within the disc, often exserted in male flowers; Ovary superior, l-3(-8)-celled, lobed or not; Ovules 1 or 2 per locule, ascending, anatropous, campylotropous or amphitropous. Fruits capsular or drupaceous, or consisting of 2 or 3 samaras, when capsular usually loculicidal, rarely septicidal or septifragal. 1-3-celled, lobed or not, outside smooth, or wrinkled, or with warts, knobs, or spines.
Seeds globose to obovoid, sometimes compressed, often with an arillode or a sarcotesta; Usually covered by an arillode, either called a sarcotesta (when adnate to the exotesta) or an arillode (when free from the exotesta). See Van der Pijl (1955, 1957, 1966). In Guioa, Mischocarpus, and to a lesser extent Sarcopteryx the arillode is usually provided with an appendage (pseudo-funicle); endotesta often with a radicular pocket. Cotyledons either superposed above each other (notorrhizal embryo) or collateral beside each other (lomatorrhizal embryo), but there are many intermediates. (F. Adema)

Distribution

Asia-Tropical: South America: present tropical and subtropical regions of the world: present
140 genera with c. 1350 species, widespread in tropical and subtropical regions of the world, especially well represented in South America. In Malesia 42 genera with ca. 235 species.

Morphology

Indumentum. Usually consisting of solitary simple hairs, sometimes of two-branched hairs (T-hairs, Litchi), or stellate tufts of hairs (Dimocarpus, Glenniea, Harpullia)\ scale hairs (glandular scales, 'Schilffern') are found in several genera, then young axes and leaflets with a sticky (viscid) exudate. Various types of glandular hairs may be present (Adema 1991; Adema & Van der Ham 1993; Van Welzen 1989). (See also the section on leaf anatomy.)

Taxonomy

The present system of the Sapindaceae follows that developed by Radlkofer (1890, 1931-1934) with only a few changes made by Muller & Leenhouts (1976).

Radlkofer (l.c.) divided the family in two subfamilies (Eusapindaceae, Dyssapindaceae) and fourteen tribes. The subfamily Eusapindaceae was divided by him in two groups: Eusapindaceae nomophyllae and Eusapindaceae anomophyllae. In the view of Radlkofer (l.c.) the Dyssapindaceae are derived from the Eusapindaceae.

Muller & Leenhouts (1976) in their survey of the pollen types accepted most of the system of Radlkofer. The main differences are that Muller & Leenhouts combined the tribes Aphanieae and Lepisantheae and so have only thirteen tribes, and did away with the division of the Eusapindaceae, proposing a more informal grouping in three groups A, B, and C. The most important change is that the Dyssapindaceae (as Dodonaeoideae) are considered to be an assemblage of relicts and that the Eusapindaceae (as Sapindoi-deae) are more homogeneous and derived.

The families Hippocastanaceae and Aceraceae are closely related to the Sapindaceae and may be included in that family, the former as a member of the tribe Harpullieae, the latter as a tribe of their own in the Dodonaeoideae.

An enumeration of the subfamilies and tribus, and of the genera occurring in Malesia is given below.
  • A. Dodonaeoideae (= Dyssapindaceae)
    • 1. Cossinieae: -
    • 2. Dodonaeeae: Dodonaea
    • 3. Doratoxyleae: Filicium, Ganophyllum
    • 4. Harpullieae: Harpullia
    • 5. Koelreuterieae: Koelreuteria
  • B. Sapindoideae (= Eusapindaceae)
    • Group A
      • 6. Lepisantheae: Glenniea, Lepisanthes, Zollingeria
      • 7. Melicocceae: Tristira, Tristiropsis
      • 8. Sapindeae: Atalaya, Sapindus
    • Group B
      • 9. Cupanieae: Amesiodendron, Arytera, Cnesmocarpon, Cupaniopsis, Dictyoneura, Diploglottis, Elattostachys, Euphorianthus, Gloeocarpus, Gongrospermum, Guioa, Jagera, Lepiderema, Lepidopetalum, Mischocarpus, Paranephelium, Rhysotoechia, Sarcopteryx, Sarcotoechia, Synima, Toechima, Trigonachras
      • 10. Nephelieae: Alectryon, Cubilia, Dimocarpus, Litchi, Nephelium, Pometia, Xerospermum
      • 11. Schleichereae: Schleichera
    • Group C
      • 12. Paullinieae: Cardiospermum
      • 13. Thouinieae: Allophyllus
(F. Adema)

Cytology

Chemical characters of the family have recently been discussed twice (Hegnauer 1973, 1990). Radlkofer (1890) fully discussed the taxonomic meaning of the chemical characters detected by him during his painstaking anatomical investigations. It should be stressed that he predicted the wide occurrence of saponins in the family, and showed their taxon-specific location in twigs, leaves, calyces, pericarp, testa, and embryo, and their deposition in ordinary parenchymatic cells or in idioblasts of different size and shape. These idioblasts ('Secretzellen') tend to occur in many, but by no means all taxa of the family and contain mainly resinoid compounds, mucilages, tannins, or (and) saponins; in fresh tissues the content of these idioblasts was assumed to be latex-like. Radlkofer also described the distribution, size and shapes of calcium oxalate deposits in the family. Leaf and twig epidermata of Sapindaceae are sometimes mucilaginous; Radlkofer gave an exact description of the mucilage cells of the epidermis and their largely erratic occurrence in the family. The chemistry of sapin-daceous mucilages is unexplored so far. Many taxa of Dodonaea, Filicium, Ganophyllum and Llagunoa have sticky, viscid exudates on leaves and twigs.

Recent phytochemical results with sapindaceous plants demonstrate clearly that their chemical characters have much to offer to botanists looking for infrafamiliar and inter-familiar affinities.

As already mentioned saponins occur widely in the family. The ichthyotoxic and de-tergent properties known from a large number of species are mainly derived from their saponins. Today the chemistry of these saponins is rather well known. Mono- and bidesmo-sidic saponins occur and their sapogenins are oleanene-type pentacyclic triterpenic acids such as oleanolic, medicagenic, and zanhic acids, and hederagenin, or polyhydroxylated derivates of beta-amyrin such as barringtogenol, Rl-barrigenol, and camelliagenin-A. Sapindaceous saponins are often acylated in the sapogenin- and/or sugar-part; acetic, angelic, and other acids are acylating agents. Steroidal sapogenins have not so far been found in the family. The resinous exudates of Dodonaea taxa contain labdanoid and clero-danoid diterpenes, and triterpenes of the lupane-series. Lupeol, betulin, and betulinic acid were isolated from the bark of Schleichera oleosa.

Accumulation of large amounts of quebrachitol, a monomethyl ether of 1-inositol (= [-]-chiro-inositol) in leaves, barks, flowers, and fruits is highly characteristic of the family. This character is shared with Aceraceae and some Hippocastanaceae.

Polyphenolic compounds seem to be accumulated in the family mainly in the form of coumarins (e.g. scopoletin), coumarinolignans (e.g. cleomiscosin-A), flavonoids, proan-thocyanidins (formerly leucoanthocyanidins), and tannins. Leaves of several taxa yielded glycosides of the flavonols kaempferol, quercetin, isorhamnetin, and sometimes myricetin, and of the flavone luteolin. Cuticular waxes and resinous exudates of Dodonaea species contain lipophilic flavonoids such as the prenylated and O-methylated kaempferol derivatives viscosol and aliarin, and di- and trimethyl ethers of kaempferol (e.g. santin), and of 6-hydroxykaempferol (e.g. penduletin). A flavanone, pinocembrin, was also isolated from twigs of Dodonaea viscosa. Oligomeric proanthocyanidins and condensed tannins seem to be more or less ubiquitous; they are mainly based on procyanidins, but may also contain prodelphinidins. Hydrolysable gallotannins do also occur in Sapindaceae. Fruits of Harpullia pendula yielded gallic acid, m-digallic acid, and galloyl glucoses, and very recently the C-glucosidic gallic acid derivatives bergenin and 11-O-galloylbergenin were isolated from leaves of Allophylus edulis var. edulis []. The tannin content of dry bark may reach 15-20% and tannin-rich sapindaceous barks are used locally as tanning agents. As previously mentioned, tannins are sometimes deposited in idioblasts or so-called tannin sacs.

Sapindaceae store fatty oils, proteins, starch, and/or amyloid in taxon-specific combinations and amounts in their embryos (there is no endosperm as was early noted by Radlkofer). Amyloid is known only from Cardiospermum. Large amounts of starch or fatty oils seem to occur vicariously. From a taxonomic point of view the fatty oils seem to be the most interesting storage products of seeds. Three main types of seed oils can be distinguished within the family: a) Oils which consist of the usual triglycerides only; b) oils which also contain non-cyanogenic cyanolipids; c) oils which consist of triglycerides and cyanogenic cyanolipids; b- and c-type oils are taxonomic markers of Sapindaceae. In cyanolipids the triol glycerin is replaced by a leucine-derived mono- or diol with a branched C5-skeleton, one double bond, and a terminal cyano group, e.g. HO-CH2- C(CH3)=CH-CN (= x). The difference between the non-cyanogenic (e.g. with alcohol x) and cyanogenic cyanolipids consists in the presence of a so-called cyanohydrin group in the alcohol part of the latter, e.g. CH2-C(CH3)-CH(OR)-CN (= y; R = H = alcohol, in casu a mono-ol).

Cyanohydrins spontaneously release HCN; therefore an oil with the cyanolipid y with R = CO-(CH2)18-CH3 yields on saponification the cyanogenic alcohol y with R = H. Obviously oils with cyanogenic cyanolipids are more or less toxic. Moreover, seed oils of Sapindaceae often contain unusual main fatty acids; arachidic, 11-eicosenoic, and dihydrosterculic acids are reported in literature. Arachidic and eicosenoic acids are preferentially combined with C5-alcohols, i.e. incorporated in cyanolipids, but may also be main fatty acids in oils without cyanolipids, such as the seed oil of Blighia sapida. A thorough analysis of the composition of the seed oils of a large number of taxa could be expected to disclose valuable characters for infrafamiliar classification.

Cyanolipids are structurally and bio synthetically linked with a third group of toxic constituents, the cyanogenic glucosides. If in y R is a glucosyl residue, the hydrophilic cyanogenic glucoside heterodendrin of Heterodendrum oleaefolium and other taxa results. Many Sapindaceae contain cyanogenic glucosides in dangerous amounts. Leaves of Heterodendrum oleaefolium can yield as much as 0.38% HCN (dry wt). The cyanoglu- cosides cardiospermin, its sulphate (ester with sulphuric acid), and heterodendrin (= di- hydroacacipetalin) have been isolated from Cardiospermum grandiflorum and Heterodendrum oleaefolium. In the former species such glucosides occur throughout the plant. Probably all parts (including defatted seeds) of sapindaceous plants, which are cyanogenic, contain such glucosides; these have aglyca (i.e. cyanohydrins) identical or nearly so with the alcohols esterified with fatty acids in cyanogenic cyanolipids. In ripe seeds of many Sapindaceae cyanoglucosides are replaced by cyanolipids; others may have cyanoglucosides in place of cyanolipids. Cyanoglucosides such as heterodendrin form a biochemical link between Sapindaceae and Leguminosae (acacipetalin and heterodendrin in a number of Acacia species) and Rosaceae-Spiraeoideae (cardiospermin-type glucosides in Sorbaria).

A fourth type of toxic principles in the family is represented by hypoglycin-A and biosynthetically related nonproteinogenic amino acids, such as alpha-(methylenecyclo-propyl)-glycine. They have a branched carbon chain of 6 or 7 C-atoms, and occur free or as glutamyl peptides in seeds and other parts of certain Aceraceae, Hippocastanaceae, and Sapindaceae. Hypoglycin-A was isolated for the first time from the 'edible' aril of Blighia sapida (Ackee tree) and subsequently traced as the cause of an intoxication known as 'Jamaica vomiting sickness'. The biogenetic origin of these amino acids has not yet been established with certainty. They were thought to be derived from leucine or isoleucine, but results of recent biogenetic investigations (Kean & Lewis 1981) make another pathway more probable. Threonine, a C4 hydroxyamino acid, and two C1-unit supplied by methionine, would give the skeleton of the C6 amino acid alpha-(methylenecyclopropyl)-glycine which is accumulated, for instance, in seeds of Litchi chinensis. Elongation of the chain of this amino acid by a mechanism known from glucosinolates should then result in hypoglycin-type C7 amino acids.

Finally some poorly known or erratically occurring classes of compounds should be mentioned. Essential oils were isolated from leaves of Serjania piscatoria, a fish poison plant, and S. serrata, from the wood of Exothea copalillo and from Allophylus edulis (= A. cobbe), but their composition is not yet known. Radlkofer gave lengthy descriptions of glandular hairs and excretory cells (idioblasts) of sapindaceous plants. These anatomical characters fully agree with the production and accumulation of essential oils by some members of the family.

Positive alkaloid reactions are reported in literature for a rather large number of Sapindaceae, but isolation and identification of alkaloid-like compounds are rare. Phenyl-acetamide was isolated from leaves of Allophylus cobbe and purine alkaloids (caffeine, theobromine, theophylline) accumulate in large amounts in seeds and other parts of some species of Paullinia (P. cupana, P. sorbilis, P. triantennata, P. yoco).

Fresh pericarps of Blighia sapida yielded a quinonoid substance named blighione C16H20O8); its structure has not yet been elucidated.

In summary, production and accumulation of quebrachitol, cyanolipids, cardiospermin-type cyanoglycosides and hypoglycin-type amino acids are biochemical markers of the family which indicate affinities with Aceraceae and Hippo cast anaceae on one side and with Leguminosae and the rosalean stock on the other. (R. Hegnauer)
Some tens of chromosome numbers of mainly South American Sapindaceae are known and are listed below.

Apparently polyploidy is scarce in the family. So far, only one certain case of tetra-ploidy has been found for Urvillea uniloba var. uniloba (Sapindoideae-Paullinieae; Fer-ruci 1981a). Ferruci (1985) also made two counts for Allophylus edulis (Sapindoideae-Thouinieae), once 2n = 14 was found and once 2n = 28. The first count, 2n = 14, is doubtful as it is exceptional among all other Sapindaceae', quite likely, a haploid set of chromosomes was counted erroneously as a diploid set. The species complex Allophylus cobbe (of which A. edulis is a synonym) is probably not a polyploid complex as suggested by Leenhouts [].

The basic chromosome numbers vary between x = 10 and x = 18. The tribes which are considered to show more derived characters, like Paullinieae and Thouinieae, tend to have the lower basic numbers. The following chromosome base-numbers are a compilation from literature. (P.C. van Welzen & P.W. Leenhouts)
DodonaeoideaeX = 10, 11, 12, 14, 15, 16
CossinieaeX = 10
LlagunoaX = 10
DodonaeeaeX = 14, 15,(16)
DodonaeaX = 14, 15,(16)
DoratoxyleaeX = 16
FiliciumX = 16
HarpullieaeX = 12, 15, 16
HarpulliaX = 15
MagoniaX = 15
MajideaX = 12
UngnadiaX = 16
XanthocerasX = 15
KoelreuterieaeX = 11, 15, 16
KoelreuteriaX = 11, 15, 16
Sapindoideae X = (11), 10, 11, 12 J, 13, 14, 15, 16, 18
Group AX = 13, 14, 15, 16, 18
LepisantheaeX = 13, 14, 15, 16
ChytranthusX = 16
LepisanthesX = 13, 14, 15
PancoviaX = 16
MelicocceaeX = 16
MelicoccaX = 16
SapindeaeX = 11, 15, 18
DeinbolliaX = 15
SapindusX = 11, 15, 18
Group BX = 11, 14, 15, 16
CupanieaeX = 14, 16
AporrhizaX = 14
BlighiaX = 16
CupaniaX = 16
NephelieaeX = 11, 14, 15, 16
AlectryonX = 16
DimocarpusX = 15
LitchiX = 14, 15
NepheliumX = 11
XerospermumX = 16
SchleichereaeX = 15, 16
SchleicheraX = 15, 16
Group CX = (7?), 10, 11, 12, 14
PaullinieaeX = 10, 11, 12
CardiospermumX = 10, 11
HoussayanthusX = 12
PaulliniaX = 12
SerjaniaX = 12
UrvilleaX = 11
ThouinieaeX = (7?), 14
AllophylusX = (7?), 14

Uses

The wood of several species is used for timber. (See also paragraph on wood anatomy, p. 425.) Various species are used in medicine, as vegetable, as soap (Sapindus saponaria) or fish poison. The family includes ornamentals such as species of Cardiosper-mum, Dictyoneura, Filicium, Koelreuteria, Lepisanthes. Some species are planted as gar-den fence (Dodonaea angustifolia), or as shade trees (Dodonaea angustifolia, Filicium).

However, Sapindaceae are more important as a source of edible fruits and seeds. The juicy arillode or sarcotesta is particularly appreciated. Of economic importance, and hence widely cultivated, are Dimocarpus longan (Longan), Litchi chinensis (Litchi, Lychee) and Nephelium lappaceum (Rambutan). (F. Adema)

Citation

Backer & Bakh. f. - in Fl. Java. 1965: 130
S.T. Reynolds - in Fl. Austral. 1985: 4
Abdulla - in Fl. W. Pakistan. 1973: 1
Law Yuh-wu, Lo Hsin-shui, Wu Young-fen & Chen Te-chao - in Fl. Reip. Pop. Sinicae. 1985: 1
Radlk. - in Engl., Pflanzenr. 98. 1931-1934: 1