Acalypha wilkesiana Müll.Arg.

Muñoz, Iris Montero, Levin, Geoffrey A. & Cardiel, José María, 2023, Monograph of Acalypha L. (Euphorbiaceae) of the Western Indian Ocean Region, with the description of a new species from Mayotte, Adansonia (3) 45 (26), pp. 395-496 : 485-486

49. Acalypha wilkesiana Müll.Arg.

Prodromus Systematis Naturalis Regni Vegetabilis 15 (2): 817 ( Müller Argoviensis 1866), nom. cons. prop. Ricinocarpus wilkesianus (Müll. Arg.) Kuntze, Revisio Generum Plantarum 2: 618 ( Kuntze 1891). — Acalypha amentacea Roxb. subsp. wilkesiana (Müll.Arg.) Fosberg & Sachet, Smithsonian Contributions to Botany 45: 10 ( Fosberg & Sachet 1980). — Type: Fiji. “in insulis Fidji”, s.d., Wilkes Expedition s.n. (U.S. Expl. Exped. under Capt. Wilkes) (lecto-, designated in Cardiel et al. 2022a: G-DC [one specimen over two sheets: G00324021 and G00324022]; isolecto-, GH[GH00045512], K[K000959008], US[US00096423, US00096424]).

ICONOGRAPHY. — André & Bois (1907: 358); Fig. 73H.

ETYMOLOGY. — The epithet honors American naval officer and explorer Charles Wilkes (1798-1877).

DISTRIBUTION AND HABITAT. — Native to Melanesia. Widely cultivated as ornamental plant throughout the tropics. Cultivated species in Madagascar (Analamanga and Vakinankaratra), Mascarene Islands ( La Réunion) and Seychelles ( Mahé) ( Fig. 74 ).

PRELIMINARY CONSERVATION ASSESSMENT. — Acalypha wilkesiana is a widespread cultivated ornamental but is not known in the wild. Is considered native of Melanesia but of unknown origin ( Sagun et al. 2010). It sometimes is found along forest edges and roads. We assess this species as Least Concern (LC).

MATERIAL EXAMINED. — 8 collections. Madagascar. Anonymous 11 (P[P05546985]); Anonymous s.n. (P[P05546986]); d’Alleizette, Ch. 705 (P[P04779510]); Rotereau, L. s.n. (P[P05510219]).

La Réunion. Séverin 68 (P[P04779511]).

Seychelles. Jeffrey, C. 606 (K); Thomasset, H.P. s.n. (K).

REFERENCES. — Robertson (1989: 200); Montero Muñoz et al. (2018a: 112).

DESCRIPTION

Shrubs or small trees, probably evergreen, to 4 m tall, monoecious. Branches usually tomentose to substrigose, sometimes also hispid, glabrescent when mature. Axillary buds naked, hispid with simple, erect trichomes. Stipules to 7(-10) mm long, linear-lanceolate or filiform, sometimes broadened at base, appressed-pubescent. Petioles 1-4(-8) cm long, tomentose. Leaf blades usually variegated green, red, yellow, purple, or copper, 8-20 × 3-10(-13) cm, usually broadly ovate-lanceolate, sometimes elliptic or obovate-lanceolate, membranous; base broadly cuneate, obtuse, or rounded, sometimes decurrent; apex acuminate, sometimes abruptly so, acumen to 40 mm long, obtuse, mucronate; margin serrate to crenate-serrate, teeth obtuse, irregular; upper and lower surfaces subglabrous, appressed-pubescent on veins; venation actinodromous, basal veins 3 or 5, secondary veins 7-9 per side. Stipels absent. Inflorescences spiciform, unisexual, axillary. Male inflorescences to 25 cm long; peduncle to 15 mm long, velutinous; flowers glomerate; bracts to 1 mm long, elliptic, sparsely hairy. Female inflorescences to 10 cm long, densely flowered; peduncle to 40 mm long, pubescent with simple, curved trichomes; bracts to 16, sessile, enlarging in fruit to 9 × 11 mm, sparsely hairy; margin deeply dentate, teeth c. 15, to 1/2 bract length, triangular-lanceolate, central tooth prominent; bracteoles absent. Male flowers: pedicel to 1 mm long, sparsely hairy; buds to 1 mm diameter, sparsely hairy. Female flowers 1 per bract, sessile; sepals 3, to 1 mm long, elliptic-lanceolate, puberulent; ovary c. 1.3 mm diameter, 3-lobed, smooth, surface densely pubescent; styles 3, to 7 mm long, distinct, glabrous, each divided into 8-10 segments. Allomorphic flowers not seen. Capsules to 5 mm diameter, verrucose, surface densely pubescent. Seeds c. 2 mm diameter, globose, minutely foveolate.

Figures

FIG. 73. — Mature female bracts:A, Acalypha spachiana Baill. (H. Humbert 19791); B, A. tremula I.Montero & Cardiel (R. Randrianaivo et al. 1160); C, A. urophylla Boivin ex Baill. (J. Goudot s.n.); D, A. urophylla (J. M. Hildebrandt 2914); E, F, A. urophylla (S. Malcomber 1746); G, A. vulneraria Baill. (F. Randriatafika 812); H, A. wilkesiana Müll.Arg. (Sagun et al. 2010; Sagun & Risna SR50). Illustration by Iris Montero Muñoz. Scale bars: 1 mm.

FIG. 74. — Distribution map of Acalypha wilkesiana Müll.Arg. in Madagascar and Mascarene Islands.