Chamaecrista desvauxii var. mollissima (Benth.) H.S.Irwin & Barneby
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Authors
Howard S. Irwin, Rupert C. Barneby
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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.
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Family
Caesalpiniaceae
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Scientific Name
Chamaecrista desvauxii var. mollissima (Benth.) H.S.Irwin & Barneby
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Type
Cassia desvauxii var. (B) mollissima Bentham in Martius, Fl. Bras. 15(2): 157. 1870.—"in provincia S. Paulo: Weir, Burchell, Silva Manso."—Lectoholotypus (Irwin, 1964, p. 101): Weir 205, K - NY Neg. 1515. C. tetraphylla var. mollissima (Bentham) Irwin, Me
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Synonyms
Cassia desvauxii var. mollissima Benth., Cassia lanceolata Collad., Cassia tetraphylla Martyn, Chamaecrista persoonii (Collad.) Greene, Cassia pulchra Kunth, Cassia tecta Vogel, Chamaecrista madrensis Rose, Cassia madrensis (Rose) H.S.Irwin, Cassia bartlettii Standl., Cassia tetraphylla var. longifolia Amshoff, Cassia tetraphylla var. colombiana H.S.Irwin, Cassia desvauxii Collad., Cassia tetraphylla Desv. var. tetraphylla
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Description
Species Description - When adult frutescent or suffruticose, branched from base or distally, the stems erect or incurved-ascending (2.5-)4—14(—25) dm, sometimes precociously flowering from a single stem branched distally; foliage usually olivaceous, rarely glaucescent, either glabrous, or glabrous and pilosulous-ciliolate, or sparsely to densely, even velutinous-pilosulous on both faces, sometimes the proximal lvs glabrous but those of distal branchlets pilosulous, the vesture pallid or rarely fulvescent; larger stipules (3—)5—15(—18) x 2.5-7(-8) mm, when relatively small ovate-acute or -acuminate, half or less than half as long as internodes, when larger ovate- oblong or broadly lanceolate acute or deltately subacute, subequally to slightly longer than internodes, persistent; lf-stalk of larger lvs (4-)5—11(—12) mm, those of some late-season branchlets sometimes shorter, the petiole (3-)4-8(-ll), the rachis 1-3 mm; gland scutellate or saucer-shaped (0.3-)0.5-2 mm diam, mostly sessile but (especially in s.-centr. Goiás) sometimes shortly stout-stipitate, then in profile shortly peg-, tack- or trumpet-shaped to 0.7(-l) mm tall but not or scarcely longer than diam of head; larger lfts obovate to oblanceolate obtuse or obtuse mucronulate 13-34 x (3.5—)4.5— 14(— 16) mm, ±(1.5-)2-4 times longer than wide, the distal pair ±1/5-½longer than the proximal; pedicels (12-) 15-35(-42) mm, commonly as long or longer, rarely shorter than leaf, mostly as long or longer, rarely shorter than longer sepals; long sepal (12-) 13-21 (-24) mm; long petal (12-)14-24(-27) mm; pod 30-50 x 6-8(-10) mm, the sutures always at least puberulent, the valves varying from glabrous to strigulose or pilosulous, sparsely or densely so, the vesture pallid or yellowish; ovules (10)12-20(-24).
Distribution and Ecology - Moist or seasonally dry campo, savanna, and brushy grassland transitional to woodland, in Mexico and Central America entering open pine-forest, ascending from near sea level on the Atlantic Coastal Plain of the Guianas where found on sandy low-level terraces from just above clay alluvium, and the lower Amazon valley up to ± 1000 m in Mexico, to 1500 m on the Eastern Cordillera in Colombia and on the Guayana Highland, and up to 1300 m on the Brazilian Planalto (Chapada dos Veadeiros and Sa. do Espinhaço), interruptedly widespread over much of tropical South America e. of the Andes and disjunct n.-ward in Belize and Mexico; very local in Mexico on Sas. Madre Occidental (Nayarit) and Sur (Guerrero) and on the coastal plain of Tabasco (near Huimanguillo); on the Maya Mts., Belize and probably adjoining Guatemala; Cordilleras Oriental and Central in Colombia (Norte de Santander, Santander, Caldas); Guayana Highland in Venezuela (Amazonas, Bolívar) and adjacent Guyana and Terr. do Roraima; coastal and interior (campina) sands in Surinam, French Guiana and lower Amazonian Brazil (Pará); and s.-ward over the Brazilian shield from the upper Guaporé in Rondônia, Sa. do Roncador in Mato Grosso, Sa. do Cachimbo in s.-w. Pará, and s. Ceará to Paraguay, n. Argentina (Misiones) and n.-e. Paraná.—Fl. in equatorial latitudes almost throughout the year, s.-ward mostly XII-IV, n.-ward mostly X-III, especially during and after rains.
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Discussion
Our present comprehensive concept of the often misleadingly named var. mollissima accommodates not only the original pubescent type described from São Paulo but also the otherwise identical glabrous or subglabrous one which passed until recently as Cassia tetraphylla var. tetraphylla (or var. longifolia Amsh.). It is equivalent to the broad-leaved, large-flowered C. desvauxii sensu Bentham deprived of its var. brevipes which, differing essentially only in the abbreviated pedicels, has from the very beginning included both glabrous and pubescent phases. In the last revision (Irwin, 1964, p. 101) var. mollissima was so construed as to appear endemic to southeastern Brazil and adjoining Paraguay and Argentina, the similar plants from the Guayana Highland being interpreted as minor variants of sympatric glabrous var. tetraphylla. It remains true in the light of intensive new exploration that whole populations of pilosulous plants are much more frequent from central Goiás southward than elsewhere in the range of var. mollissima sens, lat.; but it now seems theoretically illogical and is in practice impossible to distinguish these from the parallel form of Guayana mentioned by Irwin (1964, p. 101, variant 1), unless the source of the plant is known. Individual plants in which glabrous young foliage gives way in lateral mature branchlets to densely pilosulous foliage (as in the holotypus of C. piauhiensis, which = Ch. desvauxii var. latifolia) demonstrate the plastic nature of pubescence in this, as in related species. A hypothesis of introgression between purely glabrous and purely pubescent species is in context of sect. Xerocalyx or the whole genus Chamaecrista no longer required to explain sudden loss or gain of trichomes.
Much of the phenetic variation encountered in var. mollissima sens. lat. was analyzed in detail by Irwin (1964, sub var. tetraphylla) and needs no repetition. Ample new collections from the Brazilian Planalto confirm the passage, imperceptibly gradual, from broad-leaved, large-flowered var. mollissima to narrowleaved, slightly smaller-flowered C. langsdorfii, herein reduced to coordinate varietal rank within Ch. desvauxii. An exceptionally large-flowered and ampleleaved glabrous var. mollissima is now known from several collections from Sa. do Roncador (e.g. Ratter et al. 1396; Irwin et al. 16215); this simulates var. glauca, but has stipules of var. mollissima or var. langsdorfii. Serra dos Pireneus and vicinity has yielded a glabrous var. mollissima with distinctly though stoutly stipitate petiolar glands (cf. Irwin et al. 18537, 18649, 18706) suggestive of a trend that culminated in var. peronadenia on Sa. Dourada, but the gland, shorter and coarser, and here associated with stipules and leaves of var. mollissima not of var. glauca. However, the variety of such minor modifications present on the Planalto seems virtually inexhaustible.
Our reduction to synonymy of taxa recognized in 1964 requires commentary: a) Cassia tecta, already known to Vogel in gray-pubescent (typical) and brownish- pubescent 08) phases, cannot be maintained on basis of hair-color. It may be visualized as a form intermediate between ideal var. mollissima and var langsdorfii, resembling the latter in the thatch of relatively long, often but not invariably overlapping stipules that covers the stems (whence the epithet). On Sa. do Cipó typical C. tecta is associated with a habitally similar and obviously closely related glabrous plant with the same stipules but larger flowers, this indistinguishable technically from glabrous var. mollissima sens. lat. These two forms as observed in the field seemed to contribute, as also sympatric var. malacophylla, pubescent like C. tecta but prostrate, to a complex introgressive community within which no taxonomic lines could be drawn. The situation on Sa. do Cipó will not be understood without detailed biosystematic studies, b) Cassia madrensis was described from an almost flowerless plant collected the first week of August, that is at the beginning of the rainy season in Sa. Madre Occidental, and we think it probable that its microphyllous aspect, which can be matched on late season branchlets of var. mollissima from Venezuela and Brazil, is due to this circumstance. No tetraphyllous xerocalyx has been collected subsequently in Nayarit and the only other gathering from Mexico (Guerrero, Hinton 11192, collected in flower in January) is exactly duplicated by material of var. mollissima from the Guayana Highland (e.g. Altson 538, NY). Ovate as opposed to narrowly ovate to lanceolate bracteoles, used to separate C. madrensis and C. bartlettii collectively from C. tetraphylla sens, lat., no longer provide an effective differential character. For note on disjunct dispersal of C. madrensis see under var. le. c) C. bartlettii seemed at the time of description safely distinct from anything described in the then new revision of Cassia in North American Flora and was not compared with South American C. desvauxii, of which it seems to us certainly only a series of displaced populations. Similar disjunctions of range between Mexico, Belize and northern South America are encountered in Ch. (Absus) zygophylloides (Guayana Highland, Belize, Oaxaca) and Ch. viscosa (Guerrero, Colombia) and must reflect past migrations of relatively xerophytic floras at a period when tropical rain-forest was in retreat.
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Objects
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Distribution
Mexico North America| Colombia South America| Belize Central America| Nayarit Mexico North America| Guerrero Mexico North America| Tabasco Mexico North America| Norte de Santander Colombia South America| Santander Colombia South America| Caldas Colombia South America| Colombia South America| Venezuela South America| Amazonas Venezuela South America| Bolívar Venezuela South America| Roraima Brazil South America| French Guiana South America| Pará Brazil South America| Amazonas Brazil South America| Paraguay South America| Misiones Argentina South America| Argentina South America|