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(Last Modified On 3/18/2013)
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(Last Modified On 3/18/2013)
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Species
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Cnidoscolus urens (L.) Arthur
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PlaceOfPublication
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Torreya 21: 11, 1921.-Fig. 8.
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Synonym
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Jatropha urens L., Sp. PI. 1007, 1753. Jatropha adenophila Pax & Hoffm., Pflanzenreich 63 (IV, 147, VII): 400, 1919. Cnidoscolus adenophilus (Pax & Hoffm.) Pax & Hoffm., Naturl. Pflanzenfam. ed. 2, 19c: 166, 1931.
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Description
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Herb or softly woody subshrub 0.5-2 m high; stems densely armed with rigid stinging hairs 2-6 mm long. Leaves chartaceous; petioles mostly 3-12(-15) cm long, pubescent, sparsely to densely armed; junction of petiole and blade with a dense cluster (1.5-3 mm wide) of small digitiform glands; stipules split into a central subulate greenish part 2-5 mm long and several small lateral glands or gland-tipped setae; blades ovate or suborbicular in outline, 3-5-lobed, ? cordate at base, ca (5-)7-15 cm long, 8-18 cm broad, 5-7-palmatinerved, pubescent (often more densely so beneath), with stinging hairs along veins, the lobes oblong to obovate, obscurely to sharply denticulate, abruptly acute to acuminate. Dichasia terminal (or pseudoaxillary due to sympodial growth); peduncles sparsely to densely armed, 3.5-12 cm long; pistillate flowers ca 3-6 per inflorescence, at proxi- mal axils; staminate flowers ca 10-25 per inflorescence, clustered at tips of second- order branches. Staminate flowers subsessile (pedicels to 1 mm long); perianth greenish-white, unarmed, oblong-urceolate in bud, ca 11-13.5 mm long (in Panamanian specimens); perianth tube cylindric, basally dilated, ca 3-7.5 mm long, unarmed, glabrous to densely pubescent, the lobes suborbicular to ovate or broadly elliptic, ca 3-6 mm long, rounded, unarmed or with I or 2 stinging hairs, moderately to densely pubescent without (rarely glabrous); disc pulviniform, closely adnate to the base of the staminal column, densely hispidulous, 1 mm wide or more; stamens 10, biseriate, the outer series with filaments free, ca 3.5-4 mm long, the inner series with filaments ca 6.5-8.0 mm long, connate more than half- way into a column, the anthers elliptic, 1.3-1.5 mm long; staminodes filiform, ca 1.5-2.5 mm long. Pistillate flowers nearly sessile, pedicels becoming 1-4 mm long in fruit; sepals distinct, whitish, oblong, caducous, 2.8-3 mm long; disc a small annular ring ca 0.2 mm high; ovary pubescent and usually armate, sometimes glabrous, the styles nearly free, ca 1.2-1.3 mm long, incrassate, twice bifid. Capsules usually armed with stinging hairs, more or less rugose, ca 10-12 mm long; seeds oblong- obovate, somewhat compressed, 6.5-9.7 mm long, 3.5-5.1 mm broad, pale to dark brownish or grayish, more or less flecked, minutely rugulose, distinctly beaked, the caruncle deltoid, 1.2-1.5 mm high, 2-3 mm broad.
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Distribution
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Widely distributed from eastern Mexico south to Argentina, Paraguay, and Brazil.
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Specimen
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CANAL ZONE: Balboa, Standley 25485 (US); Curundu, McDaniel 5180 (MO), Tysorn 1045 (MO); Farfan Beach, Dwyer 3065 (MO), Tyson 1803 (MO); Gamboa, Pittier 3712 (US); Matachin, Kuntze 1921 (NY, US); vic of Miraflores Locks, King 5321 (TEX), Stern et al. 81 (DAV, MO). COCLE: banks of Rio Grande, Burch et al. 1157 (MO); wet lianos betw Aguadulce and Anton, Woodson et al. 1226a (A, MO, NY). DARIEN: ViC of El Real, Rio Tuira, Stern et al. 454 (DAV, MO). HERRERA: Chitre to Divisa, Burch et al. 1357 (MO). LOS SANTOS: Monagre beach, ca 5 mi SE of Los Santos, Lewis et al. 1673 (DAV, GH, MO, US). PANAMA: Chepo, Dodge 10728 (F, MO), Duke 4061 (MO), Pittier 4740 (US, type coll. of C. adenophilus); Las Margaritas to Rio Mamoni, Duke 5867 (MO); nr Jenine, Rio Canita, Duke 3821 (MO); 13 mi SE of La Chorrera, King 5259 (TEX); betw Las Sabanas & Matias Hernandez, Standley 31815 (US); Panama, Hayes 295 (NY); San Jose I, Erlanson 41 (GH), Harlow 82 (GH); Johnston 197 (GH); Taboga I, Macbride 2773 (F, US). VERAGUAS: hwy to Sona, 29 mi W of Santiago, King 5279 (TEX).
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Note
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The Panamanian populations of C. urens are not only as proteanly variable as elsewhere in much of tropical America, but appear to fall into a bimodal varia- tion pattern in which the extremes appear as though they were distinct species. West of the Canal Zone and on the islands in the Gulf of Panama appears a form with predominantly 5-lobed leaves densely pubescent beneath, large staminate flowers with long anthers (1.1 mm or more), and relatively large seeds up to 9.3 mm long, while in the Canal Zone and to the east are found plants with smaller mostly 3-lobed glabrescent leaves and smaller staminate flowers (anthers 0.6-0.8 mm) and seeds (mostly 6.5-7 mm long). It is this small-flowered form which was described by Pax and Hoffmann as a new species, C. adenophilus, partly on the basis of a bracteal character which seems to be nonexistent. Although it might appear that two species are present in Panama if one compared a few sheets of the large-flowered form (e.g. Burch et al. 1157, D'wyer 3065, Johnston 197, Lewis et al. 1673) with sheets of the small-flowered form (e.g. Duke 5867, Pittier 3712, Stern et al. 81, Tyson 1045), closer inspection will show that the readily apparent morphological differences are not sufficiently closely cor- related to permit the delimitation of two different species. In other parts of Mexico and Central America a similar kind of bimodal variation pattern occurs, but there too the characters do not show any geographically distinctive correlation. The varieties recognized by Mueller and by Pax and Hoffmann appear merely to repre- sent individually striking biotypes rather than geographic races. The cytological study by Miller and Webster (Brittonia 18: 378, 1967) showed n = 18 in both small-flowered and large-flowered forms, although since only 3 populations were sampled, further counts would be desirable. The infraspecific variation of C. urens thus remains a baffling unsolved problem which evidently requires a considerably more sophisticated analysis than it has received so far.
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