Monographs Details: Senna guatemalensis var. calcarea 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.
Description:Variety Description - Pilosulous with incurved-ascending yellowish hairs up to 0.3-0.55 mm; gland solitary between first pair of lfts; longer lfts ovate or lance-ovate, at apex deltate- or triangular acute (2.8-)4-7.5 x 1.5-2.2 cm, 2.1-3.7 times as long as wide; racemes 20—35-fld, the axis and peduncle together 9-15 cm; outer sepals ±4.5 mm, the inner ones 6 mm; longer petals 7.5-8 mm; pod and seed unknown.—Collections: 4. [Key: "Racemes 20-70-fld, the fruiting axis 3-16 cm; s.-centr. Guatemala and n.-w. into Mexico.2. Lfts 6-9 pairs; pod 9.5-12 mm wide; areole of seed-face 2-3.5 mm wide; highland Guatemala, from Sa. de Cuchumatanes to dept. Chimaltenango. Lfts 3-6(-7) pairs; allopatric, and if pod as wide then the areole narrower; Mexico. Lfts lance-ovate, deltate- or triangular-acute. Petiolar gland between proximal pair only; s.-w. Tamaulipas (Sa. de Guatemala) Mexico."]

Distribution and Ecology - Humid pine-oak forest on karst limestone, 1500-1700 m, descending on rio Guayalejo to 300 m, known only from Sa. de Guatemala, a spur of Sa. Madre Oriental near 23°20'N in s.-w. Tamaulipas.

Discussion:The var. calcarea, the northernmost known expression of S. guatemalensis, derives from its ovate acute leaflets a facies distinct from all other forms of its species. Otherwise it closely resembles var. hidalgensis, especially in the solitary petiolar gland and in form of the inflorescence, but a close comparison of the flowers reveals in var. calcarea slightly shorter petals (the longest 7.5-8, not 8-11.5 mm) and decidedly shorter anthers, those of the 3 abaxial stamens 3-3.5 (not 4-4.5) mm long. Sierra de Guatemala lies about 180 km north of the nearest known station for var. hidalgensis, the range of which is separated from that of var. calcarea by the depression in the Sierra crest formed by the barrancas of the Rio Verde system.
Distribution:Tamaulipas Mexico North America|