Croton orinocensis Müller Argoviensis (1873: 135)

Caruzo, Maria Beatriz Rossi & Cordeiro, Inês, 2013, Taxonomic revision of Croton section Cleodora (Euphorbiaceae), Phytotaxa 121 (1), pp. 1-41 : 26

14. Croton orinocensis Müller Argoviensis (1873: 135) ( Fig. 5D–H ). Type:— VENEZUELA. Amazonas: Habitat ad flumen Orenoco prope Maypuré , June 1854, R. Spruce 3723 (holotype G, isotypes BM, K!, P!, W) .

Croton badiocalyx Croizat (1943: 127) . Type:— COLOMBIA. Los Llanos, Boyacá, Orocué, 140 m, 12 May 1939, O. Haught 2823 (holotype A!, isotypes COL!, F!, NY!, US!) .

Shrubs to trees 1–10 m tall; latex brownish; appressed-stellate, stellate-lepidote and dendritic trichomes; branchlets cylindric, smooth, floccose, dendritic trichomes. Leaves strongly discolorous, with a pair of sessile saucer-shaped basilaminar glands; lamina 3–16.5 × 1.5–7.5 cm, elliptical, apex acuminate, base subcordate to cordate, margin entire to inconspicuously serrate, usually with glands; upper surface glabrescent, scattered simple trichomes, lower surface lepidote, silvery, scattered rufous-silvery trichomes on midvein, appressedstellate and stellate-lepidote trichomes; venation pinnate, brochidodromous; petiole 0.7–2.7 cm long; stipules ca. 2 mm long, entire, triangular. Inflorescences 2.5–4 cm long, terminal, congested; inflorescence axis cylindric, striate, pubescent, stellate trichomes; proximal cymules bisexual, with 1 pistillate flower and 1 staminate flower, distal cymules with 1 staminate flower; bracts 3–7 mm long, margin lacerate, with glands, ovate, apex acuminate, prophylls 2–4 mm long, linear-lanceolate. Staminate flowers ca. 7 mm long, campanulate, pedicellate; pedicels ca. 3 mm long; calyx ca. 4 mm long, lepidote externally, rufousferrugineous, appressed-stellate trichomes, glabrate internally; calyx lobes 5, united up to half of their length, then free for ca. 2 mm, entire, equal, valvate, triangular, apex acute, margin villose; petals ca. 4 mm long, linear-lanceolate, apex rounded, villose externally; disk 5-segmented; stamens ca. 15, filaments subulate, ciliate, anthers ellipsoid; receptacle villose with simple trichomes. Pistillate flowers 0.6–1 cm long, campanulate, pedicellate; pedicels 2–3 mm long; calyx 4–8 mm long, lepidote externally, rufous-ferrugineous, appressed-stellate trichomes, glabrescent internally; calyx lobes 5, united at the base, then free for the terminal 3–7 mm long, entire, equal, imbricate, ovate, apex acute to acuminate; petals absent; disk 5-segmented; ovary globose, hirsute-tomentose, long stalked stellate trichomes; styles 3, 4-fid, united at the base, each one entire up to half of their length then branching into 12 terminal arms, covered by stellate trichomes, included in calyx. Fruits ca. 1 cm long, subglobose, warty, appressed-stellate trichomes, calyx lobes inconspicuously accrescent; seeds ca. 4 mm long, subglobose, ribbed.

Distribution and habitat: — Croton orinocensis is an Amazonian species from “terra firme” forests of Colombia, Venezuela and Brazil, growing at 70–300 m elevation.

Phenology:— Flowering in January, February, April, May, July, November and December; fruiting in February, June, August and December.

Taxonomic notes: —The species is most similar to Croton spruceanus . Despite the similarity between both species, mainly regarding their vegetative features, Croton orinocensis differs from C. spruceanus by its inflorescences (congested in C. orinocensis vs lax in C. spruceanus ), pistillate flowers (campanulate in C. orinocensis vs urn-shaped in C. spruceanus ), and calyx in fruit (inconspicuously accrescent in C. orinocensis vs conspicuously accrescent in C. spruceanus ).

Selected specimens examined: — COLOMBIA. Meta: Orocué , Rio Meta, fl., 3 November 1933, J. Cuatrecasas 4399 ( US) . VENEZUELA. Amazonas: Carretera Pto. Ayacucho hacia Samariapo , Cerro Tigrito , entre Platanillal y Guayabal al oeste de la carretera, 5°23’N e 67°41’W, 6 January 1993, A. Gröger 672 (MO, TFVA, VEN) . BRAZIL. Pará : Sete Varas airstrip on Rio Curua, 54°92’W e 0°95’S, fr., 4 August 1981, J.J. Strudwick et al. 4088 (INPA, MG, MO, NY, US) .

Figures

FIGURE 5. A–C. Croton organensis. A. Flowering branch, detail of basilaminar gland and serrate foliar margin (Caruzo et al. 72). B. Details of flattened branchlets and stipule (Caruzo et al. 72). C. Pistillate flower (Caruzo et al. 72). D–H. Croton orinocensis. D. Flowering branch, detail of foliar trichomes (Gentry & Berry 14581). E. Stipule (Gentry & Berry 14581). F. floral bract (Gentry & Berry 14581). G. Young fruit (Gentry & Berry 14581). H. Mature fruit (Gentry & Berry 14581).