Chamaecrista nictitans subsp. brachypoda

  • Title

    Chamaecrista nictitans subsp. brachypoda

  • Authors

    Howard S. Irwin, Rupert C. Barneby

  • Scientific Name

    Chamaecrista nictitans subsp. brachypoda (Benth.) H.S.Irwin & Barneby

  • Description

    51/I. Chamaecrista nictitans (Linnaeus) Moench subsp. brachypoda (Bentham) Irwin & Barneby, stat. nov. Cassia brachypoda Bentham in Martius, Fl. Bras. 15(2): 172. 1870.—"Habitat in prov. Minas Geraes campis ad S. João del Rey et versus Rio S. Francisco: Martius; ad Caxoeira do Campo: Claussen; in eadem provincia: Weddell; ad Montes Claros: Pohl, in prov. Goyaz collibus siccis ad Conceição et in virgultosis prope Arrayas: Gardner n. 3684, 3686.; ad Goyaz et Porto Imperial ad fl. Tocantins. Burchell. Crescit etiam in Boliviae prov. Chiquitos: D’Orbigny."—Lectoholotypus, Gardner 3686, collected at Arrayas, II.1840, fl, fr, K (hb. Benth.)! = NY Neg. 9190; isotypus, K (hb! Hook.)! IAP Neg. 1129, paratypi, omnes manu Benth. determinati: Weddell 1056, G, P; Claussen 14.155, K; Pohl 1116, K! = NY Neg. 1540; Burchell 6686, 8774, K! Martius s.n. e S. João d’El Rey, M!— D’Orbigny s.n. e Bolivia, P, = Ch. repens.

    Relatively coarse, amply leafy, monocarpic, with usually only 1 erect stem at anthesis (4—)5-16(-20) dm, simple or strictly few-branched near or beyond middle, except for often glabrous upper face of lfts puberulent throughout with forwardly or incumbently incurved hairs to 0.3-0.9 mm, the stems and lf-stalks sometimes in addition finely, sometimes densely pilose with widely ascending or horizontal setae to 1—2.4 mm, the foliage dull olivaceous concolorous, the lfts usually closely lineolate-venulose.

    Stipules erect, narrowly lance-acuminate (6—)7—17 mm, at oblique base (l-)1.2-2.3(—2.5) mm wide, the blades becoming thinly papery but persistent, from base (7-)8-13(-15)-nerved, always pubescent or pilosulous dorsally.

    Major cauline lvs to (4-)4.5-9(-10) cm, short-petiolate, the expanded blade oblong or ovate-oblong in outline; petiole including pulvinus (3—)4—9(— 10) mm, above the gland open-sulcate, narrowly margined, 0.4-0.8 mm diam; petiolar glands l(-2), situated near or above middle of petiole proper, usually sessile, scutellate or shallowly patelliform but highly variable in size and outline, (0.5-)0.7-3(-3.6) mm diam, when less than 1 mm diam round, when longer elliptic, locally (especially in Mato Grosso) smaller, tack-shaped or turbinate and only 0.3-0.5 mm diam, 0.3-0.6 mm tall; often additional 1-several smaller tack-shaped or urceolate glands on distal one or all segments of rachis; lfts of major lvs 6—12(—14) pairs, well-spaced along rachis, in outline oblong, oblong-elliptic, rarely ovate-oblong, or the distal pair sometimes obliquely obovate, commonly obtuse mucronulate or aristulate, rarely deltately subacute, the longer of each plant to 12-26 x 3.5-9 mm, at base broadly cordate on proximal and cuneate to rounded on distal side, from base (4-)5-7(-9)-nerved by straight midrib with on its wide side 3-5, on its narrow one l(-2) short incurved-ascending primaries, the subcentric or moderately excentric costa dividing the blade 1 :(1—) 1.1—1.75, penniveined with 5— 11 (— 12) pairs of major secondary venules and often as many prominulous intercalary ones, when all venulation prominulous the blades becoming closely lineolate, the venation commonly prominulous both above and below but often more sharply so beneath.

    Peduncles 6-30 mm, adnate to stem for 5.5-28 mm, (1—)2—4(—5)-fld; pedicels at anthesis 3—9(—11) mm, in fruit incurved-erect 4—12(—15) mm, bracteolate 1.5—3 mm below calyx; bracteoles lance-acuminate 2.5—6 mm; buds ovoid-acuminate pilosulous; sepals often fuscous or reddish externally, lance-acuminate to ovate- acute, the longer ones 8.5—14.5 mm; petals yellow, often not strongly differentiated, the 3 adaxial (or all but the cucullus) obovate-cuneate to elliptic-oblanceolate, (7—)8—15 x 5-8 mm, the longer abaxial petal up to 8-14(-16) mm, the cucullus obliquely semi-obovate or broadly falcate-oblanceolate 7.5—14 x 7—13 mm; stamens 10, the long anthers to 6-9.5 mm; ovary densely appressed-pilosulous; style linear or almost so, (3—)4—7 x 0.3—0.5 mm; ovules (9—)11—21.

    Pod erect linear, usually slightly curved outward, (30—)35—65(—78) x 4—5(—5.5) mm, the green, reddish or atrocastaneous, finally nigrescent valves finely pilosulous or (especially along sutures) setose with spreading-ascending, rarely incurved hairs up to 0.4-1.4(-2.1) mm; seeds 2.6-3.7 mm, the testa fuscous or black, dull to moderately lustrous, lineolate-pitted.—Collections: 67.

    Thickets in cerrado, sandy, sometimes seasonally flooded campo, and becoming weedy in disturbed cerradão, on river-banks, in rough pastures and along highways (200-)400-l 100 m, widespread over the Brazilian Planalto from the middle Tocantins valley near 8°S in s.-e. Pará s. and s.-e. to the headwaters of Rio São Francisco in s.-centr. Minas Gerais and the valley of Rio Tieté in centr. São Paulo, s.-w. and w. through Sa. do Roncador and Sa. de Maracajú to extreme s.-e. Mato Grosso and adjacent Paraguay; and interruptedly to s.-e. Bolivia (near 62°W in prov. Santa Cruz).—Fl. X-VI(-VII).

    Of all forms of Ch. nictitans found to the south of the Amazonian Hylaea, subsp. brachypoda is perhaps the most easily recognized by a combination of one simple or weakly branched stem rising wandlike from a monocarpic root, dorsally pubescent stipules, in the largest leaves only few (to 12, rarely 14) pairs of ample, subsymmetricaUy veiny leaflets, and longistyled, in context of the species as a whole, large flowers. In habit and flower-size it has everything in common with sympatric large-flowered races of subsp. patellaria var. paraguariensis which, however, differs in its externally glabrous stipules and in comparable adult leaves much more numerous (at least 20, and up to 40) pairs of leaflets. In foliage it resembles Ch. repens var. repens, found immediately to the south and west and perhaps marginally sympatric around this periphery of its range; but var. repens has several, shorter stems arising from a perennial root, again dorsally glabrous stipules, and a petiolar gland raised on a pediment wider than itself. Chamaecrista venturiana, hardly different from Ch. repens in life-form and stipules, has the gland almost of subsp. brachypoda but once again fewer and in addition more oblique and more simply venulose leaflets.

    The petiolar gland of subsp. brachypoda is extraordinarily polymorphic. Most commonly it takes the same form as that of var. paraguariensis, that is a shield or shallow dish, round when small but often greatly dilated lengthwise, and either strictly sessile within the expanded sulcus of the petiole or resting as it were directly on the petiolar wings, no stipe being visible in profile. In south-central Minas Gerais and again far distant in east-central and southern Mato Grosso, the gland abruptly becomes much smaller, turbinate or tack-shaped and about as broad as tall, sometimes distinctly even though shortly stipitate, and especially in Sa. do Roncador in Mato Grosso is accompanied on one or all segments of the leaf-rachis by further glands of similar form. Size and number of glands are not correlated with any other morphological feature so that here, as in the case of Ch. glandulosa, we can derive from them no taxonomic benefits or insights. Most of the populations of subsp. brachypoda known from Sa. do Roncador and vicinity are further peculiar for a relatively dense and long setose pubescence not equalled elsewhere in the range of the subspecies. One of these (Irwin et al. 16500) has bizarre teratological flowers with many perianth and some androecial members transformed into leaflike and stemlike structures.