Monographs Details: Senna mollissima (Humb. & Bonpl. ex Willd.) H.S.Irwin & Barneby var. mollissima
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 mollissima Willd., Cassia canescens Kunth, Cassia laeta Kunth, Cathartocarpus laetus (Kunth) G.Don, Cassia atomaria L., Cassia siliquosa F.Aresch., Cassia weberbaueri J.F.Macbr.
Description:Variety Description - Characters as given in key to varieties. [Key: "Longer lvs (1.1 -) 1.5-2.5(-2.8) dm, their rachis (1.5-)2.5-12(-14) cm, the lfts 2-4(-5) pairs; racemes 15-35-fld, the axis becoming 5-18(-23) cm; oblique abaxial petal 26-36 mm; n.-w. Peru and s. Ecuador."]-Collections: 32.

Distribution and Ecology - Arid tropical scrub forest and thickets along streams, sometimes on rocky river banks or stream-beds, 5-1250(-1800) m, locally common on the coastal plain and Andean piedmont in s. Ecuador (s.-ward from near 2°S both on the coast and along the Guayas estuary) and n.-w. Peru (Tumbes and Piura), thence locally e. across the Piura-Huancabamba divide to dry valleys of the Maranon basin in n. Cajamarca (Rio Chamaya) and adjoining Amazonas (Rio Utcubamba in prov. Bagua); collected once in the highlands of Bolivia (La Paz, Rusby 1042, NY), where presumably cultivated.-Fl. throughout the year, the fruit often contemporaneous with flowers.

Discussion:The var. mollissima is superficially very similar to Mexican var. glabrata but has on the average shorter (mature) leaves, leaflets fewer by one or two pairs, and flowers at once fewer and larger. Because the raceme axis is relatively short, the expanded flowers are usually raised to the level of succeeding buds which, consequently, do not form the exserted, narrowly conical spike characteristic of var. glabrata. The specimens of var. mollissima seen by Bentham prior to 1871 were scanty and ambiguous. The typus of Cassia laeta from Guayaquil consists of one large mature leaf and two detached flowering racemes; that of C. canescens from the same place consists of a young flowering branchlet and a detached pod. This pod is indistinguishable from that of S. atomaria and, we suppose, was the decisive factor in Bentham’s misinterpretation of C. canescens as conspecific with the common Caribbean species. There is no modern evidence that genuine S. atomaria occurs in Ecuador or that there is more than one senna of its group native on the Pacific lowlands in equatorial latitudes. We are confident that Humboldt’s two specimens represent aspects of one entity. A collector in the Bosque Nacional de Tumbes (D. R. Simpson 503, NY) reports that browsing animals will eat the pods of var. mollissima but suffer loss of hair from this diet.
Distribution:Tumbes Peru South America| Piura Peru South America| Cajamarca Peru South America| Amazonas Peru South America| La Paz Bolivia South America| Ecuador South America|

Common Names:Machete de burro, machetilla, vainilla de montana, chapra