Croton hemiargyreus Müller Argoviensis (1865: 81)

Caruzo, Maria Beatriz Rossi & Cordeiro, Inês, 2013, Taxonomic revision of Croton section Cleodora (Euphorbiaceae), Phytotaxa 121 (1), pp. 1-41 : 8-10

Selected specimens examined: — BRAZIL. Minas Gerais: Bocaina de Minas, distrito de Mirantão, margem esquerda do rio Preto , fazenda Mauá, cerca de 1500 m, fl., 9 January 1988, R.B. Pineschi 348 ( GUA). 3. Croton hemiargyreus Müller Argoviensis (1865: 81) ( Fig. 3F–I ). Type :— BRAZIL. Minas Gerais: Caldas, 18

January 1857, A.F. Regnell 402 (lectoype S!, designated by Caruzo & Cordeiro 2007: 580, isolectotypes A!, F!,

G!, GH!, K!, NY!, P!, R!, US!, WU!); 1845, J.F. Widgren 339 (syntypes A!, GH!) .

Croton hemiargyreus var. gymnodiscus Müller Argoviensis (1873: 88) . Type:— BRAZIL. Rio de Janeiro: s.dat., H.W. Schott 4650 (holotype W!, isotypes A!, F!, G-DC!).

Shrubs to treelets 1.5–10 m tall; latex clear; indument silvery, lepidote subentire trichomes and dentate-lepidote porrect trichomes; branchlets cylindric, striate, lepidote, silvery. Leaves discolorous, with a pair of stalked saucer-shaped acropetiolar glands; lamina 3–18 × 1.5–13 cm, upper surface green, glabrescent, with scattered pale trichomes and lower surface silvery, lower surface densely lepidote, silvery, ovate to cordate, apex acuminate to long acuminate, base rounded to cordate, margin slighly to strongly serrate, usually with glands; venation pinnate, brochidodromous; petiole 1–9 cm long; stipules ca. 8 mm long, linear-lanceolate, deciduous. Inflorescences 4–10 cm long, terminal, lax; inflorescence axis appressed, striate, lepidote, silvery, lepidote subentire trichomes; proximal cymules bisexual, with 1 pistillate flower and 1–2 staminate flowers, distal cymules with ca. 3 staminate flowers; bracts 2–4 mm long, entire, ovate-lanceolate, prophylls lanceolate, inconspicuous. Staminate flowers ca. 7 mm long, campanulate; pedicels ca. 4 mm long; calyx ca. 3 mm long, lepidote externally, lepidote subentire trichomes, glabrate internally; calyx lobes 5, entire, equal, valvate, united up to half of their lenght, ca. 2 mm long, triangular, apex acute, margins villose; petals ca. 3 mm long, spathulate, apex rounded, margins villose; disk 5-segmented; stamens ca. 15, filaments subulate, villose, simple trichomes, anthers globose-ellipsoid; receptacle villose with simple trichomes. Pistillate flowers ca. 6 mm long, campanulate, short pedicellate; pedicels ca. 1 mm long; calyx ca. 5 mm long, lepidote externally, silvery, lepidote subentire trichomes, glabrate internally; calyx lobes 5, united at the base, ca. 3 mm long, entire, equal, fleshy, quincuncial, broadly ovate, apex acute, margin reflexed; petals reduced to ellipsoid glands; disk entire, deeply 5-lobed; ovary globose, lepidote, dentate-lepidote porrect trichomes; styles 3, 4(6)-fid, united at the base, then branching into 12(18) terminal arms, exserted from calyx, with dentate-lepidote trichomes at the base. Fruits ca. 1.5 cm long, globose, smooth, lepidote, dentate-lepidote porrect trichomes, calyx and pedicel conspicuously accrescent, reflexed in mature fruit; seeds ca. 6 mm long, globose-ellipsoid, slightly ribbed.

Distribution and habitat: — Croton hemiargyreus has a disjunct distribution between “brejo de altitude” forests in the state of Pernambuco, in northeastern Brazil, and montane pluvial forests in Minas Gerais, Rio de Janeiro and São Paulo, in southeastern Brazil, at 920–1030 m elevation. In the state of Rio de Janeiro, it is known only from the type of C. hemiargyreus var. gymnodiscos , which does not have a precise indication of locality.

Phenology:— Flowering in January, March, April and December; fruiting in January and April.

Taxonomic notes: —The species is recognized by its cordate discolorous leaves, strongly silvery on lower surface. Croton hemiargyreus is similar to C. campanulatus and C. salutaris , but differs from them in several features (see Table 1).

Selected specimens examined: — BRAZIL. Pernambuco: Brejo da Madre de Deus, Mata do Bituri , 8°12’27’’–8°12’415’’S e 36°23’730’’-36°23’320’’W, 920–1030 m, fl., 15 January 2001, L.M. Nascimento & A.G. da Silva 473 (JPB, PEUFR, RB, SP) .

Figures

FIGURE 3. A–E. Croton fragrantulus. A. Flowering branch, detail of the acropetiolar glands (Nee 40099). B. Pistillate flower (Nee 40099). C. Disk at the base of the gynoecium (Nee 40099). D. Staminate flower (Foster 424). E. Stamen, dorsal and ventral views (Foster 424). F–I. Croton hemiargyreus. F. Flowering branch, detail of the acropetiolar glands and serrate foliar margin (Caruzo et al. 116). G. Pistillate flower (Caruzo et al. 116). H. Gynoecium and reduced petal (Caruzo et al. 116). I. Fruit (Caruzo et al. 114).