Cenostigma
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Ordo: Fabales
Familia: Leguminosae
Name
Cenostigma Tul., Ann. Sci. Nat., Bot., sér. 2. 20: 140. 1843, descr. emended E. Gagnon & G. P. Lewis – Wikispecies link – Pensoft Profile
- Poincianella Britton & Rose. 1930, pro parte, excluding the type.
Diagnosis
Cenostigma is morphologically most similar to the genus Erythrostemon. It differs from the latter by its leaves with alternate to subopposite (occasionally opposite) leaflets (vs. leaflets consistently opposite in Erythrostemon). A number of other characters can help to distinguish between the two genera, but these are not constant across species of Cenostigma. For example, a stellate indumentum on the leaflets, inflorescences, and/or sepals is found on some, but not all Cenostigma species, but is always lacking in Erythrostemon. Black subepidermal glands (visible with a × 20 lens) can be found scattered in the undersurface of leaflets and/or on sepals in Cenostigma (vs. these always lacking in Erythrostemon). Cenostigma pods are generally woody with thickened margins or an adaxial, proximal woody ridge or crest (vs. less robust pods lacking any woody ridge or crest in Erythrostemon).
Type
Emended description
Unarmed multi-stemmed shrubs, small compact trees, (0.3–) 0.5–6 m, or large trees to 35 m tall, the larger trees with fluted trunks at maturity (Cenostigma bracteosum, Cenostigma pluviosum, Cenostigma eriostachys, Cenostigma tocantinum and Cenostigma macrophyllum); bark smooth, or occasionally rough and flaking (some infraspecific taxa of Cenostigma pluviosum), brown, grey, or mottled silver or grey; young shoots terete, glabrous to pubescent, glandular to eglandular. Stipules red, with ciliate margins, broadly ovate with a rounded apex, and caducous in Cenostigma pyramidale, not seen in other species. Leaves alternate, pinnate or bipinnate and then ending in a pair of pinnae plus a single terminal pinna, glabrous to densely pubescent, sometimes with stellate hairs or various types of sessile or stalked glands; petioles (0.1–) 0.6–4.8 (–6) cm, rachis 0.5–17 (– 26.5) cm; species with pinnate leaves (Cenostigma tocantinum, Cenostigma marginatum, Cenostigma pinnatum, and Cenostigma macrophyllum) either with three leaflets or 2–9 pairs of opposite leaflets; species with bipinnate leaves with 1–11 pairs of opposite to alternate pinnae, plus a terminal pinna, each pinna with 3–29 alternate to subopposite (occasionally opposite) individual leaflets; leaflets vary greatly in size, 0.5–15 × 0.1–7 cm, glossy on the upper surface, usually more or less coriaceous (chartaceous in Cenostigma tocantinum), ovate-elliptic, lanceolate with an acute to acuminate apex (some specimens of Cenostigma tocantinum), obovate, oblong-elliptic or suborbicular, apex rounded or emarginate, mucronate, base cuneate, cordate or truncate, the blade often inequilateral at the base, eglandular, or with black subepidermal glands (visible with a × 20 lens) scattered on the undersurface, and/or with conspicuous, sessile or punctate glands on the undersurface or along the margins, in addition to stipitate glands; veins usually prominent, main vein often excentric, secondary venation brochidodromous. Inflorescences either axillary or terminal racemes, these sometimes pyramidal in shape, sometimes aggregated into large showy panicles, inflorescence rachis and pedicels densely tomentose to glabrescent, sometimes covered in stellate hairs, these occasionally intermixed with stipitate glands; pedicels 5–22 mm long, articulated; bracts 2.5–6 mm long, caducous. Flowers bisexual, zygomorphic; calyx a short hypanthium with 5 sepals, 4.5–9 (– 11) mm long, the lower cucullate sepal generally slightly longer than the other four, apices entire or with a fimbriate-glandular margin, puberulous or tomentose, sometimes with a dense stellate indumentum (Cenostigma eriostachys, Cenostigma tocantinum and Cenostigma macrophyllum), the sepal lobes eglandular or with scattered dark, subepidermal glands, caducous, but the hypanthium persisting as a calyx ring in fruit; all 5 petals free and clawed, bright yellow, the median petal (7.5–) 9–15 (– 19) × 5–13 (– 17) mm, with red or orange markings on the inner surface of the blade, suborbicular to elliptic or spathulate, with a thickened, pubescent claw, the outer surface of which has short-stalked glands, these sometimes also on the dorsal surface of the blade, lateral petals 0.9–2.7 × 0.4–2 cm, broadly elliptic, sub-rectangular, obovate or suborbicular, petal claws pubescent and with stalked-glands, these sometimes also on the dorsal surface of the blade; stamens 10, free, filaments (7–) 8–14 (–21) mm long, pubescent on lower ⅔ to ½, with short-stipitate glands along entire length (except in Cenostigma macrophyllum); ovary pubescent with glands intermixed, these sometimes obscured by the indumentum, stigma a terminal fringed-chamber. Fruits laterally compressed, coriaceous to woody pods, (3.8–) 5–14 (– 16) × 1.2–3.3 (– 3.7) cm, with conspicuously thickened margins (an adaxial, proximal woody ridge or crest in Cenostigma macrophyllum), elastically dehiscent (sometimes tardily), the valves twisting at maturity, either glabrous or pubescent, smooth or prominently reticulately veined (on herbarium specimens), usually eglandular or with a few scattered stipitate or sessile glands (densely glandular in Cenostigma microphyllum). Seeds 2–6 (– 8) per pod, ovate-elliptic to ovate-orbicular, 9–19 × (6–) 8–12 × 1–3 mm, ochre, brown, or mottled, shiny.
Geographic distribution
We recognise 20 taxa in 14 species, all of them neotropical; only two of these taxa do not require new names, while the rest are species of Caesalpinia here transferred to Cenostigma. The majority of species are found in central and NE Brazil, including parts of the Amazon. Two species extend around the circum-Amazonian arc of dry forests and adjacent cerrado, including in Paraguay, Argentina and Bolivia, and one taxon is also found in the seasonally dry inter-Andean valleys of Peru. Species are also found throughout Central America, from Panama northwards and in Mexico, extending to the Caribbean, with endemics in Cuba and Hispaniola.
Habitat
Seasonally dry tropical forest, bushland and thicket (restinga, caatinga, semi-arid thorn scrub), wooded grassland (cerrado and cerradão) and terra firme forest.
Etymology
From ceno- (Greek: empty) and stigma, presumably alluding to the chambered stigma (a character of many species of the Caesalpinia Group, and not restricted to Cenostigma).
References
Lewis (1987[1]: 34–35, 1998[2]); Freire (1994)[3]; Ulibarri (1996)[4]; De Queiroz (2009[5]: 129–130, see also under Poincianella, 121–128); Warwick and Lewis (2009)[6]; Lewis et al. (2010)[7].
Taxon Treatment
- Gagnon, E; Bruneau, A; Hughes, C; de Queiroz, L; Lewis, G; 2016: A new generic system for the pantropical Caesalpinia group (Leguminosae) PhytoKeys, (71): 1-160. doi
Images
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Other References
- ↑ Lewis G (1987) Legumes of Bahia. Kew Royal Botanic Gardens, Richmond, 1–369.
- ↑ Lewis G (1998) Caesalpinia: a revision of the Poincianella-Erythrostemon group. Kew Royal Botanic Gardens, Richmond, 1–233.
- ↑ Freire F (1994) Cenostigma tocantinum Ducke (Leg. Caes.): uma redescrição da especie. Bradea 6(36): 297–303.
- ↑ Ulibarri E (1996) Sinopsis de Caesalpinia y Hoffmannseggia (Leguminosae-Caesalpinioideae) de Sud América. Darwiniana 34(1–4): 299–348.
- ↑ De Queiroz L (2009) Leguminosas da Caatinga. Universidade Estadual de Feira de Santana and Associacao Plantas do Nordeste, Brazil, and Kew Royal Botanic Gardens, Richmond, 1–443.
- ↑ Warwick M, Lewis G (2009) A revision of Cenostigma (Leguminosae– Caesalpinioideae– Caesalpinieae), a genus endemic to Brazil. Kew Bulletin 64(1): 135–146. doi: 10.1007/s12225-008-9091-1
- ↑ Lewis G, Hughes C, Daza Yomona A, Solange Sotuyo J, Simon M (2010) Three new legumes endemic to the Marañón Valley, Perú. Kew Bulletin 65(2): 209–220. doi: 10.1007/s12225-010-9203-6
