Caesalpinieae Rchb., Fl. Germ. Excurs. 2(2): 544. 1832.
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https://dx.doi.org/10.3897/phytokeys.240.101716 |
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https://treatment.plazi.org/id/4FE071C9-0FBC-4A93-4AD5-2288AAC226C3 |
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Caesalpinieae Rchb., Fl. Germ. Excurs. 2(2): 544. 1832. |
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Tribe Caesalpinieae Rchb., Fl. Germ. Excurs. 2(2): 544. 1832.
Figs 34 View Figure 34 , 35 View Figure 35 , 36 View Figure 36 , 37 View Figure 37 , 38 View Figure 38 , 39 View Figure 39 , 40 View Figure 40 , 41 View Figure 41 , 42 View Figure 42 , 43 View Figure 43 , 44 View Figure 44 , 45 View Figure 45 , 46 View Figure 46 , 47 View Figure 47 , 48 View Figure 48 , 49 View Figure 49 , 50 View Figure 50 , 51 View Figure 51 , 52 View Figure 52 , 53 View Figure 53 , 54 View Figure 54 , 55 View Figure 55 , 56 View Figure 56 , 57 View Figure 57 , 58 View Figure 58 , 59 View Figure 59 , 60 View Figure 60 , 61 View Figure 61 , 62 View Figure 62 , 63 View Figure 63 , 64 View Figure 64 , 65 View Figure 65
Poincianeae Nakai, Chosakuronbun Mokuroku [Ord. Fam. Trib. Nov.]: 253. 1943. Type: Poinciana L. [= Caesalpinia L.]
Type.
Caesalpinia L.
Included genera
(27). Arquita Gagnon, G.P. Lewis & C.E. Hughes (5 species), Balsamocarpon Clos (1), Biancaea Tod. (6), Caesalpinia L. (9), Cenostigma Tul. (15), Cordeauxia Hemsl. (1), Coulteria Kunth (11), Denisophytum R. Vig. (8), Erythrostemon Klotzsch (31), Gelrebia Gagnon & G.P. Lewis (8), Guilandina L. (up to 20), Haematoxylum L. (5), Hererolandia Gagnon & G.P. Lewis (1), Hoffmannseggia Cav. (23), Hultholia Gagnon & G.P. Lewis (1), Libidibia (DC.) Schltdl. (7), Lophocarpinia Burkart (1), Mezoneuron Desf. (24), Moullava Adans. (4), Paubrasilia Gagnon, H.C. Lima & G.P. Lewis (1), Pomaria Cav. (16), Pterolobium R. Br. ex Wight & Arn. (10), Stenodrepanum Harms (1), Stuhlmannia Taub. (1), Tara Molina (3), Ticanto Adans. (9), Zuccagnia Cav. (1).
Description.
Trees, shrubs, subshrubs, or herbs, sometimes scandent, often with prickles, thorns, glands, or glandular hairs. Stipules (best seen on young flush foliage and on seedlings) variable across the tribe, ranging from minute, lanceolate-deltate to triangular, ovate, or orbicular, sometimes foliaceous, the margins sometimes ciliate-fimbriate, persistent, caducous, or apparently lacking (at least on mature leaves). Leaves pinnate or bipinnate. Inflorescences terminal and/or axillary racemes or panicles; bracteoles absent; pedicels often jointed. Flowers zygomorphic, or rarely almost actinomorphic; hypanthium usually present (rarely a short calyx tube); sepals generally free to hypanthium-rim, the lowermost sepal modified, often forming a hood (cucullate) over the other four sepals in bud, imbricate to valvate; petals 5, the median (innermost) petal usually clearly differentiated; stamens 10, all similar, the filaments usually hairy, especially basally, and sometimes glandular, anthers mostly dorsifixed, introrse; pollen tricolporate monads, mostly spherical, surface reticulate and with granular-membraned margos surrounding weakly developed colpi (a margocolpus); ovary subsessile to short-stipitate, stigma usually crateriform. Fruits diverse, 1-several-seeded. Seeds, flattened, or globose.
Distribution.
The tribe is pantropical, found predominantly in seasonally dry tropical forests and shrublands, but extending in a subset of clades into tropical and warm temperate savannas, tropical wet forests, and tropical coastal habitats ( Gagnon et al. 2019).
Clade-based definition.
The most inclusive crown clade containing Caesalpinia brasiliensis L. and Erythrostemon gilliesii (Hook.) Klotzsch, but not Cassia fistula L., Dimorphandra conjugata (Splitg.) Sandwith or Mimosa sensitiva L. (Fig. 34 View Figure 34 ).
Notes.
The tribe comprises ca. 223 species (the number of species of Guilandina is unresolved) in 27 genera. The tribe Caesalpinieae was first described by Reichenbach (1832). Bentham (1865: 562) recognised the Caesalpinieae as a suborder comprising 12 tribes, one of which, the Eucaesalpinieae , included 16 genera, six of which are retained in the present circumscription of tribe Caesalpinieae . Bentham (1865: 566) divided the genus Caesalpinia into ten sections, six of which have become additional genera currently recognised in tribe Caesalpinieae ( Guilandina , Erythrostemon , Pomaria , Balsamocarpon , Coulteria and Libidibia ). Polhill and Vidal (1981) divided the tribe into eight informal generic groups, one of which, the Caesalpinia group, comprised 16 genera. The Caesalpinia group was defined by Polhill and Vidal (1981) to include genera with species that have a large variety of glandular trichomes, prickles and spines as a defense mechanism, and possessing zygomorphic flowers with a somewhat modified lower sepal and stamens crowded around the pistil. This informal Caesalpinia group remained largely intact in the account of Caesalpinieae by Lewis (2005b), although a handful of additional segregate genera were recognised from within the genus Caesalpinia sensu lato, and three genera of Polhill and Vidal’s (1981) group were transferred to the core Peltophorum group [ Conzattia Rose, Lemuropisum H. Perrier (now a synonym of Delonix Raf.) and Parkinsonia L., now tribe Schizolobieae ; see page 146], so that the Caesalpinia group then comprised 21 genera. Studies by Gagnon et al. (2013, 2015) demonstrated the non-monophyly of some of these 21 genera and Gagnon et al. (2016), based on molecular phylogenetic analyses and a robust species-level sampling, published a new generic system for the pantropical Caesalpinia group. Gagnon et al.'s (2016) Caesalpinia group clade is strongly supported by the study of Ringelberg et al. (2022; Fig. 34 View Figure 34 ) and is here reinstated as tribe Caesalpinieae in which the type genus Caesalpinia is nested.
Although there are no unique diagnostic morphological synapomorphies for the Caesalpinieae , it can be recognised by a combination of features, including the presence of glandular trichomes, prickles or spines, bilaterally symmetrical flowers with a somewhat modified lower sepal, and free stamens crowded around the pistil, although none of these characters are ubiquitous within the tribe. Flowers vary greatly (Fig. 35 View Figure 35 ) and can be strongly modified depending on pollination system, and fruits across the tribe are extremely diverse (Figs 36 View Figure 36 , 37 View Figure 37 ) reflecting a striking variation in seed dispersal strategies. Some leaf, armature and fruit characteristics can be used to distinguish genera and delimit the major clades of the tribe (Fig. 38 View Figure 38 ). The phylogenomic analyses of Ringelberg et al. (2022) support two major clades in Caesalpinieae , also largely resolved in Gagnon et al. (2016), one primarily composed of species with bipinnate leaves [clade I of Gagnon et al. (2016) containing Caesalpinia s.s.] and the other grouping species with a terminal pinna [clade II of Gagnon et al. (2016) containing Cenostigma and sister genera] (Fig. 34 View Figure 34 ). The two clades above also have differing defence strategies. With the exception of the unarmed Coulteria , the bipinnate leaf clade is characterised by the presence of spines and prickles along the branches, as well as having idioblasts. Although unresolved in Gagnon et al. (2016), the spinescent Lophocarpinia , Haematoxylum and Hererolandia , are now also shown to be resolved as sister to this clade in Ringelberg et al. (2022). Likewise, the other clade is characterised by the lack of thorns, and the presence of multicellular glandular structures on the stems, leaves and/or inflorescences (very rarely found elsewhere in the Caesalpinieae , such as in the genera Coulteria , Tara and Hultholia ), and is here shown to also include the unarmed Stuhlmannia and Cordeauxia , two taxa that were unresolved in Gagnon et al. (2016). The nearly mutually exclusive distribution of external glands vs. spines+idioblasts gives some support to the idea that these structures constitute alternative plant defense strategies against herbivory ( Lersten and Curtis 1994, 1996), even though the role and function of idioblasts and secretory glands in the Caesalpinieae have yet to be studied in detail.
At the generic level, fruits are highly variable and taxonomically more useful than flowers. Several of the genera can be differentiated based on fruit characteristics. For example, the fruits of Balsamocarpon , Cordeauxia , Coulteria , Cenostigma , Guilandina , Haematoxylum , Hererolandia , Hultholia , Libidibia , Lophocarpinia , Moullava , Paubrasilia , Pterolobium and Zuccagnia are all distinctive and provide useful diagnostic synapomorphies for these genera (Figs 36 View Figure 36 , 37 View Figure 37 ). In contrast, only a few floral synapomorphies are diagnostic at the generic level: for example, Guilandina species have sepals that are valvate in bud; unisexual flowers are only present in the genera Coulteria and Guilandina ; in Balsamocarpon , Zuccagnia , and Hoffmannseggia , sepals are persistent until fruiting (Fig. 36 View Figure 36 ); and in Pomaria species, the androecium and gynoecium are cupped in the lower cucullate sepal (Fig. 35E View Figure 35 ). In general, however, floral morphology within subclades of the Caesalpinieae is highly variable reflecting differences in pollination syndromes, including examples of melittophily, chiropterophily, psychophily, phalaenophily and ornithophily, sometimes occurring among closely related congeneric species (e.g., in Caesalpinia s.s. and Erythrostemon - see Fig. 35 View Figure 35 ). These repeated floral morphologies across disparate members of the Caesalpinieae suggest convergent evolution of similar pollination modes in multiple genera across the tribe.
The pollen details of individual genera are not easily extracted from the literature because so many generic names have been reinstated from within Caesalpinia s.l., or new genera described, since the palynological study of the Caesalpinioideae by Graham and Barker (1981). In addition, the surface ornamentation of the pollen varies according to pollinator type and structural similarities occur in the pollen of species in distinct genera within the tribe. In consequence, pollen type is not recorded in the generic descriptions of this treatment.
For an exhaustive list of accepted species names and synonyms in tribe Caesalpinieae , together with their currently accepted equivalents see LPWG (2022).
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