Dialium L.

Legumes of the World. Edited by G. Lewis, B. Schrire, B. MacKinder & M. Lock. Royal Botanic Gardens, Kew. (2005)

Vernacular

jutahy, keranji

Habit

Trees

Ecology

Tropical rain forest (mainly lowland evergreen), occasionally in peat, swamp or heath forest, or coastal; a few species in monsoon forest and wooded grassland (savanna), but in drier vegetation types the species frequently occur on river margins or deep s

Distribution

previous numbers range from 40-70); pantropical (from 19°N in S Mexico and Belize to 23°S in Madagascar) with 1 sp. extra-tropical in Mozambique and S Africa; not extending E of Wallace's Line (totally absent from Australia and New Guinea); main centres of diversity in WC Africa (14 spp.; 3 spp. also in E coastal Africa, 3 spp. endemic to Madagascar) and W Malesia (4 spp. in S Thailand, Laos, Cambodia and S Vietnam, 2 spp. in Borneo, Sumatra and Malay Peninsula, 1 (-2) spp. in S India and Sri Lanka), and 1 sp. widespread in the Neotropics from S Mexico through C America to the Amazon and Atlantic forest in Brazil, extending into Colombia, Peru, Ecuador and Bolivia

Note

Irwin & Barneby (1981) described a new subtribe Dialiinae to accommodate 13 genera (including Dialium) of the Cassieae and recognised 5 subgenera in Dialium; Rojo (1982) only recognised 3 subgenera, reducing one to a section of another, and reinstating Uittienia as a separate genus. In the molecular analysis of Kajita et al. (2001), Dialium is sister to a clade which contains Apuleia, Petalostylis and Zenia; in the combined analysis of Herendeen et al. (2003a), Zenia is sister to a clade which includes several species of Dialium nested amongst which is one species of Dicorynia

Tribe Cercideae is basally branching in the Leguminosae (Bruneau et al., 2001; Herendeen et al., 2003a), as predicted by Wunderlin et al. (1981), and Cercis is the most basally branching genus in the tribe. While much taxonomic work has been carried out on the tribe in the past thirty years (e.g., Larsen et al., 1980, 1984; Wunderlin, 1976, 1979; Wunderlin et al., 1981, 1987; Zhang, 1995; Vaz, 2003; Vaz & Tozzi, 2003), few species have been included in phylogenetic analyses and inter- and intra-generic relationships are still largely unresolved with the exception of Cercis (Hao et al., 2001; Davis et al., 2002b).

Wunderlin (1979) and Wunderlin et al. (1981) divided the tribe into two subtribes, Cercidinae and Bauhiniinae, based on seed, floral and fruit characters. Walpers (1842) had already down-ranked Bauhinieae Benth. (1840) to subtribal status, thus the combination Bauhiniinae (Benth.) Wunderlin (1979) is superfluous. Polhill (1994) kept the Cercideae unchanged with two subtribes and five genera. While the Cercidinae contains three small distinct genera, Cercis, Griffonia and Adenolobus, the Bauhiniinae houses the monospecific Madagascan genus Brenierea and the large, diverse pantropical genus Bauhinia sens. lat. which has been segregated into as many as twenty-six genera by various authors (Wunderlin, 1976).

While many of the Bauhinia segregates are based on minor morphological differences, others are distinguished morphologically by a suite of characters. Britton and Rose (1930), in their account of the Caesalpiniaceae for the North American Flora, divided Bauhinia into several segregate genera, including Schnella Raddi which here is treated as a synonym of Phanera, but might prove to be distinct as indicated in recent molecular analyses by Forest (unpublished data). Britton and Killip (1936) recognised Schnella as distinct from Bauhinia in Colombia. De Wit (1956), treating ‘Malaysian Bauhinieae’, recognised Bracteolanthus, Lysiphyllum, Gigasiphon, Piliostigma, Lasiobema and Phanera as separate genera and this was largely followed by subsequent flora writers in Africa and New Guinea (e.g., Brenan, 1967; Coetzer & Ross in Ross, 1977; Verdcourt, 1979). Others have retained a more inclusive Bauhinia proposed by Wunderlin et al. (1981, 1987), e.g., Macbride (1943: 207–220) for Peru; Larsen et al. (1980) for the Flora of Cambodia, Laos and Vietnam; Larsen et al. (1984) for the Flora of Thailand; Chen (1988) for China, and Larsen & Larsen in Hou et al. (1996) in Flora Malesiana. Zhang (1995) published a morphological cladistic analysis of the series of Bauhinia sens. lat., but few species of Bauhinia have been included in molecular studies. It remains equivocal as to whether Bauhinia sens. lat. is monophyletic, but preliminary molecular results indicate that some elements should be reinstated as distinct genera (Bruneau et al., in prep.; Forest, unpubl.). This runs contrary to the findings of Larsen & Larsen in Hou et al. (1996) who concluded “that Bauhinia in the sense of Linnaeus, Bentham, De Candolle, Taubert and Hutchinson is an evolutionary unit and a very natural genus”. Larsen and Larsen also noted that Bauhinia sens. lat. presents a reticulate pattern of variation across its pantropical range (this apparently conflicting somewhat with its status as a “natural genus”). While this is undoubtedly true if the genus is considered as all-inclusive, recent studies of legume distributions in general (Schrire et al., this volume and 2005) have revealed repeated patterns of generic distribution which appear to be duplicated by at least some of the segregates of Bauhinia. If these segregates are recognised as distinct genera (as several are in this treatment) then the reticulate pattern of variation of Bauhinia is far less pronounced. More sampling at the species level in molecular analyses and more morphological studies are needed across the full pantropical range of Bauhinia sens. lat. before inter- and intra-generic relationships are clearly resolved. In the current account genera that have been recognised as distinct from Bauhinia in at least one flora treatment that post-dates De Wit (1956) have been treated as separate genera, especially where these are supported by the preliminary results from a chloroplast trnL (intron and spacer) sequence analysis (Forest, unpubl.). The reader’s attention is also alerted to the detailed infra-generic division of Bauhinia by Wunderlin et al. (1987) in their reorganisation of the Cercideae which also forms a sound basis for sampling in future studies.

Palynological studies of Bauhinia (Larsen, 1975; Schmitz, 1977; Ferguson & Pearce, 1986) have all stressed the considerable variation in pollen morphology within the genus sens. lat. and there are clear correlations between pollen exine ornamentation, floral morphology and pollination. It remains to be seen just how closely these correspond to evolutionary relationships of species. Nevertheless, Schmitz (1977) made several new combinations in segregate genera of Bauhinia based on palynological type. These included new names in Lasiobema, Lysiphyllum, Pauletia, Perlebia and Phanera (Pauletia and Perlebia here considered as synonyms of Bauhinia). Zhang (1995), who analysed morphologically the series of Bauhinia proposed by Wunderlin et al. (1987), concluded that while some supraspecific segregates of the genus were supported, none of the subgenera appeared to be monophyletic. Several realignments were proposed.

The Cercideae as presented here includes 12 genera and (322)–335–(348) species. This treatment differs from Wunderlin et al. (1981, 1987) and Polhill (1994) in that Barklya, Gigasiphon, Lasiobema, Lysiphyllum, Phanera, Piliostigma and Tylosema are considered distinct from Bauhinia. While some of these may well be reincluded in Bauhinia after further study, yet other genera may be reinstated from within Bauhinia. Bracteolanthus, treated as distinct by De Wit (1956), is here included in Lysiphyllum following Wunderlin et al. (1987), while Barklya, considered congeneric with Bauhinia by Wunderlin (1979) and Wunderlin et al. (1981, 1987) is considered distinct following George (1998b) and Forest (unpublished data). The reinstatement of Lasiobema appears least well supported (Forest, unpubl.).

Leguminosae, J. B. Gillett, R. M. Polhill & B. Verdcourt. Flora of Tropical East Africa. 1971

Morphology General Habit

Trees or (rarely) large shrubs, not climbing, unarmed

Morphology Leaves

Leaves simply imparipinnate; stipules very quickly falling; conspicuous glands absent from petiole and rhachis; leaflets 3–21, opposite to alternate

Morphology Reproductive morphology Inflorescences

Inflorescences of terminal and lateral many-flowered panicles; bracts and bracteoles small, quickly falling

Morphology Reproductive morphology Flowers

Flowers hermaphrodite, irregular, very rarely (not in East Africa) regular

Morphology Reproductive morphology Flowers Calyx

Sepals 5 (or ? 6, but very rarely and not in Flora area), imbricate

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 2 (in East African species), elsewhere sometimes up to 10; anthers basifixed, dehiscing by lateral slits

Morphology Reproductive morphology Flowers Disc

Disc (in East African species) well-developed, much wider than the ovary and ± puberulous or pubescent

Morphology Reproductive morphology Flowers Gynoecium Ovary

Ovary small, sessile or shortly stipitate, with 2 ovules

Morphology Reproductive morphology Fruits

Pod (in East African species) ± ellipsoid to subglobose, not compressed (in species outside the Flora area sometimes ± flattened), indehiscent; exocarp hard, brittle, smooth except for indumentum; mesocarp pulpy, mealy and brown-orange or red when dry

Morphology Reproductive morphology Seeds

Seeds 1–2, embedded in the mesocarp; testa smooth except for small ± irregular cracks; areoles absent; endosperm present.

M. Thulin et al. Flora of Somalia, Vol. 1-4 [updated 2008] https://plants.jstor.org/collection/FLOS

Morphology General Habit

Trees or large shrubs

Morphology Leaves

Leaves imparipinnate

Morphology Reproductive morphology Inflorescences

Flowers in many-flowered panicles

Morphology Reproductive morphology Flowers

Flowers bisexual, irregular, sometimes apetalous

Morphology Reproductive morphology Flowers Calyx

Sepals usually 5, imbricate

Morphology Reproductive morphology Flowers Androecium Stamens

Stamens 2(–10)

Morphology Reproductive morphology Flowers Disc

Disc well-developed, wider than ovary

Morphology Reproductive morphology Fruits

Pods (in Somalia) ± ellipsoid to subglobose, indehiscent, with a hard, brittle shell and a pulpy inner layer

Morphology Reproductive morphology Seeds

Seeds 1–2, smooth, except for small ± irregular cracks, without areoles.

Distribution

Some 35-40 species in the tropics, mostly West African.