Senna pinheiroi

  • Title

    Senna pinheiroi

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Senna pinheiroi H.S.Irwin & Barneby

  • Description

    41.  Senna pinheiroi Irwin & Barneby, sp. nov., inter Bacillares biglandulosas foliolis parvis (5.5 cm usque tantum longis) margine revolutis supra nitidis venulosis antherisque inter se valde inaequilongis 3 abaxialibus caeteras longe superantibus praestans.—BRAZIL. Pernambuco: thicket, Goiana ("Gayanna"), 30.V.1935 (fl), D. Bento Picket 3863.—Holotypus, F.

    Relatively small-lvd shrubs 1(-?) m with slender obtusangulate stems, the leafless annotinous ones with pallid, cracked epidermis, the annotinous densely leafy, pilose-pilosulous throughout with spreading-ascending hairs up to 0.5-1.2 mm, remotely minutely resinous-verruculose, the foliage bicolored, lustrously olivaceous and sharply venulose above, dull and densely pilosulous beneath, the subterminal inflorescence of 1-few, few-fld racemes axillary to diminished lvs or incipiently paniculate, shortly exserted.

    Stipules herbaceous erect, falcately linear-oblanceolate ±4-7 x 0.3-0.6 mm, deciduous.

    Lvs 6-10 cm; petiole including ovoid livid pulvinus 2-3.5 cm, at middle 0.8-1.2 mm diam, bluntly 5-ribbed, shallowly open-sulcate ventrally; rachis 0.6-1.2 cm, much shorter than the petiole; glands between both pairs of lfts (at least of most lvs), subsessile, in profile 2-2.7 mm tall, the reddish, narrowly ovoid glabrous head 0.5-0.9 mm diam; pulvinules ±2-2.5 mm; distal pair of lfts obliquely ovate, deltately subacute or broadly obtuse 4-5.5 x 1.7-2.8 cm, ±2.2-2.6 times as long as wide, at base broadly cordate on proximal, less deeply so on distal side, the margins strongly revolute, the slightly excentric midrib almost immersed above, cariniform beneath, the ±6-9 pairs of major camptodrome secondary veins with tertiary and reticular venulation all sharply prominulous above, the reticulation only faintly so beneath; proximal pair of lfts almost as wide but ±1/3 shorter.

    Racemes subcorymbosely 3-6-fld, the axis including peduncle ±1-2 cm; bracts narrowly lance-elliptic 3-4 mm, persistent into anthesis; pedicels at anthesis 12-22 mm; buds (not seen) presumably globose, puberulent; sepals thinly herbaceous livid-tinted, not greatly graduated, all ovate obtuse, the longest 9-10 x 5-6.2, all delicately 3-5-nerved and in age faintly reticulate; petals yellow, puberulent dorsally, subhomomorphic, the longest 20-22 mm; filaments either glabrous or puberulent, those of 4 median stamens ±1.5-2 mm, of 3 abaxial ones up to 4 mm, the glabrous anthers of 4 median stamens oblong, slightly curved, 4-5.5 mm, with divaricate beak ±0.5 mm, those of 3 abaxial ones strongly incurved 6-8 mm, with sigmoidally porrect beak ±0.8-1 mm; ovary pilosulous; style pubescent almost to the stigma, not dilated distally, at apex ±0.5 mm diam; ovules ±96-110.

    Pod unknown.—Collections: 4.

    Thickets and margins of woods on the coastal plain of Brazil, between 7°30' and 23°S, known only from e. Pernambuco (Goiana), e.-centr. Bahia (Marau; Itacare) and w. Rio de Janeiro (Restinga de Tijuca), to be sought in intervening Espirito Santo, n.-e. Bahia, Sergipe and Alagoas.—Fl. V-VI.

    Within ser. Bacillares biglandular leaf-stalks coincide with highly heteromorphic anthers only in S. pinheiroi and S. rugosa; as a consequence these two species fall together in our key to the series, but are nevertheless only fortuitously associated. In general aspect, in size and organization of the flowers and racemes, in details of the flower, and particularly in the pallid, cracking epidermis of the annotinous branchlets, S. pinheiroi seems much closer to S. tenuifolia. This is likewise coastal, but sympatric only far southward, and clearly different in its uniglandular leaf-stalks and only faintly reticulate upper face of leaflets. On the coastal plain in the same latitudes with S. pinheiroi the only other biglandular Bacillaris is S. quinquangulata, fundamentally different in the androecium and immediately distinguished by the racemose exserted inflorescence and leaves different in outline, texture and venulation. Until mature pods and seeds of S. tenuifolia and S. pinheiroi can be compared between themselves and with other, possibly related Bacillares, no more measured estimate of affinities can be attempted. The earliest collection of S. pinheiroi, from an unrecorded locality in Bahia by Blanchet (no. 1592, BM, G) was apparently not seen, or was deliberately overlooked, by Bentham.

    The species is dedicated to the gifted collector Raimundo Soares Pinheiro, field assistant at CEPEC near Ilheus, Bahia in 1965-73.