Monographs Details: Chamaecrista nictitans subsp. disadena var. pilosa
Authors:Howard S. Irwin, Rupert C. Barneby
Authority: Irwin, Howard S. & Barneby, Rupert C. 1982. The American Cassiinae. A synoptical revision of Leguminosae tribe Cassieae subtrib Cassiinae in the New World. Mem. New York Bot. Gard. 35, part 2: 455-918.
Family:Caesalpiniaceae
Synonyms:Cassia riparia var. pilosa Benth., Cassia propinqua Kunth, Cassia erecta Willd. ex Steud., Chamaecrista rekoi Britton & Rose, Chamaecrista tonduzii Britton & Rose, Cassia mayana Lundell, Chamaecrista fenixensis Britton & Rose, Cassia fenixensis (Britton & Rose) Lundell, Chamaecrista comayaguana Britton & Rose, Cassia comayaguana (Britton & Rose) Lundell, Chamaecrista conzattii Britton & Rose, Chamaecrista salvadorensis Britton, Chamaecrista stenocarpoides Britton, Cassia stenocarpoides (Britton) Lundell, Cassia stenocarpa var. stenocarpoides (Britton) Schery
Description:Species Description - Monocarpic but often long-enduring, suffrutescent in age and perhaps sometimes perennant, plastic in stature and deportment, the stems commonly erect and incurved-ascending, usually branched but sometimes simple, less often, both naturally and after browsing or cutting, diffuse or humifuse, at anthesis (1—)2—10(—13, reportedly -25) dm, commonly at once incurved-puberulent and pilose with fine spreading or spreading-incurved setae up to 0.7-2.6 mm, the lfts usually glabrous on both faces, sometimes finely pilosulous beneath and exceptionally above also, their margins minutely scabrid-ciliolate or charged with random setae up to 0.7-1 mm. Adult lvs (sometimes produced only subsequent to the early fls) up to (2-)2.5-8.5(-ll) cm; petiole 2-6 mm; petiolar gland 1, greatly variable in form, either stipitate or subsessile, the shallowly concave head 0.2-0.8 mm diam, the whole in profile varying from broadly to narrowly turbinate or urn-, trumpet- or tack-shaped, 0.2-1 mm tall and from 0.3 mm taller to 0.3 mm shorter than head’s diam; lfts of adult lvs (12—) 13—26(—29) pairs, the longer ones linear to oblanceolate, straight or subsigmoid, up to (5-)7-20(-23) x (1—) 1.2—3.5(—4) mm. Pedicels 1-3, at anthesis slenderly flexible, the solitary one or the first of a fascicle up to 5—9(—11) mm, in fruit thickened, sigmoidally spreading-incurved and up to 7—12(—14, exceptionally -18) mm; sepals up to (5-)5.3-8.3(-9.3) mm; petals usually little graduated in length, forming when fully expanded a campanulate perianth, the cucullus and long petal only slightly longer though both or at least the former much wider than the 3 adaxial ones, up to (5.5—)6— 12 mm; stamens 10, the 3 longest anthers to (3.3—)3.7—6.8(—8) mm; ovary strigulose or pilosulous, style strongly incurved, (1.4—)1.6-3(-3.3) mm, dilated at apex to 0.4-0.7 mm diam; ovules (7-) 11-24. Pod linear in outline, straight or slightly sigmoid-curved, (20-)27-67 x 2.7-4.5 mm, the castaneous or purplish, finally nigrescent valves either incurved-puberulent or less often thinly weakly pilose; seeds pale brown or pale chestnut, often fuscous-suffused or -lineolate, dull or sublustrous, 2.4-3.2 mm.—Collections: 133.—Fig. 51.

Distribution and Ecology - Thickets, shores, savanna-campos, disturbed woodlands, ascending from sea level up into the pine-oak- and rainforest, now commonest as a colonial weed along highways, in waste places, plantations and gardens, ascending in Mexico and Central America to 1200-2000, in Venezuela to 2300, and on the Brazilian Planalto to 1500 m, discontinuously widespread through much of tropical America outside the West Indies, the Amazonian Hylaea, the Guayana Highland, and most of the Andes: frequent in Central America from w. Panama (Chiriquí) to e. and s. Mexico (Tamaulipas; s. Veracruz; Nueva Galicia, Sa. Madre del Sur in Oaxaca and Guerrero); absent from the rest of Panama and Colombia, but again rather frequent in the uplands of n. Venezuela from Cord. de Mérida e. to Monagas; local in centr. Ecuador (Cotopaxi) and on the Pacific slope in n. Peru (Lamba-yeque); reappearing in e. Brazil, where highly local in n. Maranhão and (weedy) e. Pernambuco and coastal Bahia (Ilhéus), thence s. on the Atlantic slope to Rio Grande do Sul and inland to the Paraguay drainage in s.-w. Mato Grosso and Paraguay, extreme s.-e. Bolivia, and common in centr. and s. Sa. do Espinhaço s.-ward from ±16°30'.—Fl. almost throughout the year, except where inhibited or killed by drought.—Ta hata ha guazu (Guarani)

Discussion:

The essential features of our newly defined var. pilosa, originally separated from Cassia riparia and C. stenocarpa by a particular type of vesture now seen to have no real diagnostic significance, are the relatively long weak flowering pedicels, the perianth of moderate size and asymmetry, and the dilated style-tip. It is very closely related to var. jaliscensis, which has the same style, but smaller, usually more asymmetric corolla and substantially shorter pedicels, and to var. disadena, which has essentially the same flower and pedicels, but a linear and on the average longer style.

Variation within var. pilosa follows the pattern set by other members of the Ch. nictitans complex, involving great plasticity of life-form and stature, emphasis and loss of either element of the duplex vesture, and modification of the petiolar gland both in absolute size and in proportion of stalk to head. The Brittonian segregates listed in the synonymy are based on individual combinations of these variable factors:

i. Ch. rekoi: Densely pilosulous throughout, the lfts subappressed-pilose on both faces; gland trumpet-shaped, long-stalked.

ii. Ch. tonduzii: Copiously setose and puberulent, of average stature; gland

tack-shaped, short-stalked.  

iii. Ch. fenixensis: Specimens mutilated by browsing or cutting and consisting of old stems laterally regenerating, the leafy shoots bearing only immature leaves; pubescence of the last but gland smaller.

iv. Ch comayaguana: Gland of Ch. tonduzii, but growth-habit slender, diffuse, leaves relatively small, setose pubescence much reduced.

v. Ch conzattii: Habit nearly of the last, but setose pubescence copious and petiolar gland small, tack-shaped, as Ch. fenixensis; lfts relatively broad, narrowly oblong.

vi. Ch. salvadorensis: Erect, copiously setose; gland almost of Ch. tonduzii; leaflets linear-oblong.

vii. Ch. stenocarpoides: Essentially as the last, but the leaflets of Ch. conzattii.

The only one of the proposed segregates which may have some genetic substance is Ch. comayaguana, a slender diffuse small-leaved form from forest habitats above 1000 m. However the diffuse habit of growth is encountered in coarser plants at lower elevations, and typical erect var. pilosa is found also at montane elevations. The opposite extreme, a giant phase with long leaves and large flowers, reportedly reaching (in Merida, Venezuela) a stature of 2.5 m but usually not more than half as tall, occurs at random points within the Central American range of var. pilosa (cf. Breteler 3161 from Venezuela; Skutch 2880 from Costa Rica). Its ploidy level should be investigated.

Distribution:Mexico North America| Venezuela South America| Brazil South America| Panama Central America| Tamaulipas Mexico North America| Veracruz Mexico North America| Oaxaca Mexico North America| Guerrero Mexico North America| Chiriquí Panamá Central America| Ecuador South America| Cotopaxi Ecuador South America| Maranhão Brazil South America| Pernambuco Brazil South America| Rio Grande do Sul Brazil South America| Mato Grosso Brazil South America| Paraguay South America| Bolivia South America|