Senna bacillaris var. benthamiana (J.F.Macbr.) H.S.Irwin & Barneby

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 1: 1-454.

Family

Caesalpiniaceae

Scientific Name

Senna bacillaris var. benthamiana (J.F.Macbr.) H.S.Irwin & Barneby

Type

"Type, Williams 566." Holotypus, collected on Rio Nanay, prov. Maynas, dpto. Loreto, Peru, 3.V. 1929, F!

Synonyms

Cassia fruticosa var. benthamiana J.F.Macbr., Cassia hoffmannseggii Mart. ex Benth.

Description

Variety Description - Vesture of lvs and inflorescence variable, either appressed and short as in var. bacillaris or longer (hairs sometimes to 0.6 mm) and spreading- or incurved- villosulous, in either case often lutescent; lfts variably reticulate, and defined areoles in upper Amazonia often >1 mm, in Colombia and sometimes elsewhere as in var. bacillaris; functional stamens 6, the anther of the middle abaxial one much smaller than those of its neighbors, sterile; ovules 160-266.—Collections: 129. [Key: "Androecium functionally 6-merous, the anther of the centric abaxial stamen much shorter or more slender (or both) than that of its immediate neighbors, sterile; Brazilian and Peruvian Amazonia, upper Orinoco basin, and n.-w. through Colombia to Ecuador and the middle Magdalena valley."]

Distribution and Ecology - Forest margins, bush-islands in savanna and gallery woodland, commonly on seasonally flooded land (varzea and creek-banks), widely dispersed over middle and upper Amazonian Hylaea, in Brazil from w. Para (Obidos) w. and s.-w. to middle Rio Purus and into the Andean foothills of Peru (Loreto and San Martin), Ecuador (Santiago-Zamora and Napo-Pastaza), and Colombia (n. to e. Boyaca where attaining 900 m and reaching the headwaters of Rio Meta), from Brazil extending n. through the Negro-Vaupes valley into the upper Orinoco basin in Amazonas and Apure, Venezuela, and in Colombia across the e. Cordillera to middle Magdalena valley (Antioquia and Santander).—Fl. w. and n.-ward mostly XI-III, in middle Amazonia mostly III-VII, but throughout the range of dispersal irregularly through the year.

Discussion

Apart from more numerous ovules, perhaps correlated with a longer pod, the var. benthamiana is consistently distinguished from var. bacillaris only by the modified androecium, the middle one of the three abaxial, long-beaked anthers being greatly reduced in size and sterile; this character, however, is neatly correlated with dispersal. In a very general and unreliable way the variety may be said to have shorter, proportionately wider and less strongly acuminate leaflets and a yellowish- rather than gray-pubescent inflorescence which tends to be thyrsoid and leafy-bracteate rather than paniculate and exserted from foliage. Limited field-data suggest that the Amazonian plant attains when adult a more treelike stature than is common in Caribbean var. bacillaris, and the pod, still poorly known, is perhaps on the average longer and more slender, with narrower thickened borders parallel to the sutures. Pubescence in the variety, as here defined, is variable, the denser looser pilosity which Macbride emphasized as diagnostic for C. fruticosa var. benthamiana no longer seeming taxonomically significant. Within the range of var. benthamiana as defined by the androecium we find short appressed pubescence constant in Amazonia and the Rio Negro-Orinoco basins; loose vesture replaces this on the upper Solimoes in Brazil and follows the rivers upstream into Peru, only to reappear in the Andean foothills of Colombia from Rio Putumayo northward. These areas of pilosity are divided, however, by an enclave of appressed pubescence in Ecuador and the two types of vesture occur together in Magdalena valley in Colombia. We cannot divide the material seen on any feature correlated with pubescence and believe that this sort of variation can well be accommodated in one taxon. The epithet benthamiana (which would be a later homonym in specific rank) was suggested by a misunderstanding. Macbride intended to describe formally a cassia which Bentham (1871, p. 522) had referred to as "perhaps ... a broadleaved pubescent variety of C. bacillaris represented in his herbarium by Mathews 1591 from Chachapoyas, Peru, and by a miscellany of pilosulous Bacillares from Yucatan and Nicaragua which are irrelevant to our present purpose. The Mathews collection, which was Macbride’s particular concern in context of Flora of Peru, in reality represents the endemic Peruvian S. loretensis, greatly different from the holotypus of var. benthamiana in outline of the leaflets and in particular in the short pod. The earliest collections of the present var. benthamiana, all middle-Amazonian (Martius s.n. at M and Spruce 1110, 1558 in hb. Benth.) were referred by Bentham (1870, p. 104) to a mixed and imperfectly realized Cassia hoffmannseggii, a name which, by lectotypification in this paper, has become a synonym of Senna latifolia.

Common Names

Justo sin razon

Distribution

Pará Brazil South America| Loreto Peru South America| San Martín Peru South America| Santiago-Zamora Ecuador South America| Pastaza Ecuador South America| Napo Ecuador South America| Boyacá Colombia South America| Amazonas Venezuela South America| Apure Venezuela South America| Antioquia Colombia South America| Santander Colombia South America|