Senna pallida var. tuerckheimiana

  • Title

    Senna pallida var. tuerckheimiana

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna pallida var. tuerckheimiana H.S.Irwin & Barneby

  • Description

    177l. Senna pallida (Vahl) var. tuerckheimiana Irwin & Barneby, var. nov., cum var. quiedondilla necnon var. longirostrata, ambabus in montanis gua- temalensibus incolis foliolisque penninerviis (nec reticulatis) congruis, comparanda, ab ea, quoad foliola numerosa (10-13-juga usque) et legumen latum (7-8 mm) simili, petiolo abbreviato 6-13 (nec 13-30) mm longo, hac eadem notula et insuper legumine lato a var. longirostrata diversa.-GUATEMALA. Baja Verapaz: Santa Rosa, IX. 1888 (fl), H. von Tuerckheim in Donnell Smith 1422.-Holotypus, US; isotypi, MO, NY, US.

    Weak, sometimes subsarmentose shrubs 1.5-3 m, densely pilosulous with sordid or lutescent hairs to 0.4-0.6 mm, the leaflets densely pilosulous beneath, at least puberulent above, the 2-fld racemes both axillary and forming a small terminal panicle.

    Stipules erect setiform 2-6 x 0.2-0.3 mm.

    Major cauline lvs 10-15 cm (those near and in the inflorescence, not further described, smaller and simpler); petiole 6-13(-15) mm, at middle 0.6-1.3 mm, ± 1.2-1.8(-2.1) times longer than first segment of rachis; rachis 7-11 cm; gland between proximal pair 2-2.6 mm, sessile or stipitate, the stipe pilosulous, the body strongly compressed, in profile 0.7-1.2 mm wide; lfts up to 10-13 pairs, not or scarcely accrescent upward, in outline elliptic, elliptic-oblanceolate or oblanceolate, obtuse-mucronulate or deltately acute (1.8-)2.2-3.7 x 0.7-1 mm, (2.2-)3-4.2 times as long as wide, the margins strongly revolute, the venation of 5-8(-9) pairs of camptodrome and some faint intercalary secondary veins either immersed or prominulous above, finely prominulous beneath, tertiary venulation imperceptible.

    Peduncles 18-36 mm; pedicels 15-19 mm; long sepals 11-13 mm; long petals 22-32 mm; filaments glabrous or pilosulous, of 4 median stamens commonly united at base, 1.5-2.1 mm, of 3 abaxial ones free, 3.5-5 mm, the anthers of 4 median stamens 4.5-5.5 mm, sharply truncate, the lateral beak 0.3-0.5 mm, dehiscent by parallel slits, those of 3 abaxial ones 7-8.5 mm, the tubular beak 2.5-3.8 mm; style 1.5-1.8 mm.

    Stipe of pod 5-7 mm, the body 8-13 x 0.7-0.8 cm, the interseminal septa 2.5-3.5 mm apart; seeds (few seen) obovate ±4 x 2.8 mm, the areole 1.8-2 x 1.1 mm.-Collections: 7.

    Cool humid forest, 1300-1700 m, local, known only from the highlands of Que- zaltenango (Volcanes Zunil and Santa Maria) and Santa Rosa (Sta. Rosa; Salama), Guatemala.-Fl. IX-I.

    This variety is closely related to var. quiedondilla, with which it has in common relatively many, simply penniveined leaflets (in larger leaves up to 10-13 pairs) not accrescent upward along the rachis, and a broad, large-seeded pod, but is readily distinguished by the short petioles, only 1-2, not 3-5 times longer than the first interfoliolar segment of the leaf-stalk. The dense yellowish or sordid pilose pubescence seems further characteristic, but in the context of ser. Interglandulosae it would be imprudent to put diagnostic emphasis on this feature. The also related var. longirostrata is similar in ecology and in the simply veined leaflets, but these are fewer (up to 6-9 pairs) and strongly accrescent distally, and the narrow, small-seeded pod is only 4-5.2 (not 7-8) mm wide.

    Donnell Smith distributed the type-collection of var. tuerckheimiana as Cassia biflora, but later determined the holotypus (US) as C. viciifolia. The latter (distantly allopatric in Venezuela) is superficially similar in ample foliage, large flowers, and width of pod, but the median anthers dehisce by one U-shaped slit and the pod becomes fragile when ripe, breaking along transverse lines of interseminal septa.