Cassia cytisoides var. decora

Title

Cassia cytisoides var. decora

Authors

Howard S. Irwin, Rupert C. Barneby

Scientific Name

Cassia cytisoides var. decora H.S.Irwin & Barneby

Description

1g. Cassia cytisoides DeCandolle ex Colladon var. decora Irwin & Barneby, var. nov., foliis breviter petiolatis 2-foliolatis cum var. unijuga congruens sed ab ea (procul allopatrica) foliolis ambitu obovatis basi asymmetrice late cuneatis cito distinguenda. — BRAZIL. Minas Gerais: Serra do Espinhaço, ± 18 km e. of Diamantina, 1100 m, 19.111.70 (fl, fr), Irwin, Fonseca, Souza, Reis dos Santos, & Ramos 27894. - Holotypus, UB; isotypi, C, F, GH, K, NY, RB, UC, US.

Glabrous, the foliage either green or purplish and glaucous; lvs (2-)3-6.5 cm; petiole 5-17 mm; lfts 1 pair, very obliquely obovate, at base asymmetrically broadly cuneate, (1.5-)2-5.5 x (1-)1.5-3.6 cm; sepals 8-11 mm; longer plane petals 16.5-23 mm, the coiled petal 23-26 mm. — Collections: 8.

Ledges and crevices of sandstone outcrops, in thin sandy soil, 790-1175 m, locally plentiful along the e. slope of Serra do Espinhapo between Diamantina and Grao Mogol (lat. 16°30'-18^O30'S), n.-centr. Minas Gerais.

The var. decora is found in the same segment of Serra do Espinhapo as var. brachystachya but slightly to the east of it; both have been found near Grao Mogol but not together. They are instantly distinguishable by number, position, and outline of the leaflets, no doubtful or intermediate forms being known. The var. decora resembles the distantly allopatric var. unijuga in its petiolate bifoliolate leaves, but differs greatly in shape of leaflets. Probably the two forms are independently derived by parallel loss of a proximal pair of leaflets, var. unijuga perhaps from the phase of var. brachystachya found on the coast of Bahia, similar in outline of the leaflets, and var. decora from the vicariant var. brachystachya.

The variety was first collected by Martius in 1818 on the slopes of Mt. Itambe, and confused by Bentham with var. unijuga.