Jatropha excisa Griseb.

Authority

Dehgan, Bijan. 2012. . Fl. Neotrop. Monogr. 110: 1--274. (Published by NYBG Press)

Family

Euphorbiaceae

Scientific Name

Jatropha excisa Griseb.

Description

Species Description - Shrubs, to 1.5 m. tall. Stems: light gray, many-branched, erect, glabrous, bark peeling in thin, white, nearly translucent strips; latex clear, very viscid. Leaves: stipules branched, stipitate glands, 5-8 mm long; petioles green, 7-14 cm long and 1-2.2 mm in diam, upper surface with stipitate glands; blades persistent, ± orbicular in outline, 3- to 5-lobed, (8-)1.5— 13 x 5.3-10 cm, lobes ovate-elliptic, membranous, bases cordate, margins glandular-serrulate, apex apiculate, venation palmate, glabrous on adaxial surface and sparsely pubescent on abaxial. Inflorescences: terminal, few- or much-branched, few- or many-flowered, elongated, paniculate cymes with spirally arranged paracladia, peduncles of main florescences (4-)8.4-12 cm long and those of coflorescencse (1.5-)7-8.5 cm, bracts elliptic, 5-8 mm long, margins with knobshaped, stipitate glands; glabrous or pubescent on both surfaces; pedicels 1.8-2 mm long. Staminate flowers: sepals ovate-elliptic, 1.8-3.5 x 1.2-1.5 mm, distinct, margins beset with stipitate glands, apex acute-acuminate, pubescent on abaxial surface and glabrous on adaxial; corollas rotate, solid white, yellowish white, or green, fragrant, petals obovate, 4-5 x 1.5-3 mm, lower portion imbricate; stamens 8(-9), diadelphous-biseriate (5 + 3), outer series 1.3-2 mm and inner series 2-2.5 mm long, both series connate to ½ of length, anthers 0.7-0.8 mm long; basal glands ellipsoid. Pistillate flowers: like staminate but sepals 3.5-4.2 x 1.5-2 mm; petals 4.5-5.5 x 1.6-3.3 mm; carpels 3, styles 1.2-2.3 mm, distinct, yellowish; rarely 1 to several staminodia present, basal glands fusiform. Capsules: ellipsoid, 1-1.1 x 0.8-1 cm, surface glabrous, pubescent, or pilose, often with some red coloration. Seeds: creamy white with red-brown mottling, oval, 7-8 x 4-4.5 mm, caruncle large and conspicuously lobed.

Discussion

In the absence of flowers, the superficial, vegetative similarity of Jatropha excisa and J. gossypiifolia has resulted in several cases of incorrect identification of the species. However, one specimen was annotated as J. gossypiifolia var. excisa f. trichocarpa nomen nudum [Argentina: Norgasta, 27 Dec 1928 ([female], [male], fr), Venturi 7941 (GH)]. The notation by Herzog on the specimen of J. thyrsantha is of notable interest: “Eine mit J. excisa Grieseb. und J. flavovirens Pax et K. Hoffm. Wervante, endemische Art Boliviens.” This may illustrate the problem of species designation, because the two species are considered to be synonyms in this monograph. Only Jatropha hippocastanifolia Croizat is considered distinct.

Distribution

From southern Santa Cruz and Tarija in Bolivia to north and northwestern provinces of Argentina. A common species, often forming large colonies in grazed, chaco forest on slopes of small hills or flat areas. Its occurrence in La Paz, Bolivia is somewhat surprising because of the colder climate at high elevations of 3300-4082 m. Flowering and fruiting nearly all year but primarily during spring and summer.

Bolivia South America| Argentina South America|