Senna guatemalensis var. hidalgensis

  • Title

    Senna guatemalensis var. hidalgensis

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna guatemalensis var. hidalgensis H.S.Irwin & Barneby

  • Description

    94e. Senna guatemalensis (Donnell Smith) var. hidalgensis Irwin & Barneby, var. nov., a var. guatemalensi, cui caeterius persimilis, glandula petiolari singula, foliolis saepissime minus numerosis 3-5(-7)-jugis, floribus majoribus (petalis 8-11.5 nec 6-6.5 mm longis) necnon leguminis valvulis intus inter semina septis angustis instructis abstans.—MEXICO. Hidalgo: 10 mi n. of Zimapan, 29.VIII. 1957, (fr), H. S. Irwin 1343.— Holotypus, NY; isotypus, MICH.

    Thinly strigulose-pilosulous with hairs to 0.6-1.2 mm, the basal angle of midrib on dorsal side of lfts always more densely pilose; gland between proximal pair of lfts only; long lfts broadly obovate or elliptic-obovate 3-7 x 2-3.7 cm, ±1.5-2 times as long as wide; racemes and fls of var. guatemalensis except the sepals less strongly graduated, the outer 4-5 mm, the inner 5.5-6 mm long; longer petals 8-11.5 mm; style 0.7-1 mm; stipe of pod ±2 mm, the body 6.5-8 x 0.8-1.1 cm, the interseminal septa 0.5-1 mm high.—Collections: 7.

    Mixed pine-oak-juniper woodland, coming out onto roadsides, ±1900-2500 m, local on the Gulf slope of Sa. Madre Oriental, in drainage of Rio Moctezuma, n.-w. Hidalgo.—Fl. VII-VIII.

    A combination of solitary petiolar glands, 3-5 pairs of ample obovate leaflets and the inflorescence of var. guatemalensis neatly characterize this local Mexican senna. The pod is exactly that of var. guatemalensis except for the internal development of distinct cross-walls between the individual seed-cavities, and the seed itself is marked by a narrower areole 1-1.5 (not 2-3.5) mm wide. Probably more closely related are the geographically nearer vars. scopulorum and calcarea, both of which have solitary petiolar glands. For differences see discussion of the varieties preceding and following.

    The var. hidalgensis was collected first in Mexico, very likely near Zimapan by Thomas Coulter. The specimens (K), which now lack locality data, were referred by Bentham (1871, p. 541) to his mixed concept of Cassia botteriana and said to have originated in Nayarit ("between San Bias and Tepic").