Dalechampia bidentata Blume

van Welzen, P. C. & Winkel, E., 2022, The Malesian species of Dalechampia (Euphorbiaceae), Blumea 67 (1), pp. 26-32 : 27-29

1. Dalechampia bidentata Blume — Fig. 1

Dalechampia bidentata Blume (1825) 632; Miq.(1859) 417; Müll.Arg.(1866) 1243;J.J.Sm. (1910) 531,756;Pax & K.Hoffm.(1919) 31; Backer & Bakh.f. (1963) 493; Airy Shaw (1969) 121, (1972) 251; Govaerts et al. (2000) 549; S.S. Larsen (2005) 227, plate XII: 2. ― Dalechampia bidentata Blume var. genuina Pax & K.Hoffm. (1919) 32, nom. inval. ― Lectotype (designated here): Blume 691 (lecto L (L.2212090)!), [ Indonesia,] Java; see note 1.

[ Croton acerrimus Reinw. ex Blume (1823) 104, nom. nud.]

Dalechampia bidentata Blume var. yunnanensis Pax & K.Hoffm. (1919) 32. ― Syntypes: A. Henry 12354 ( A00047585 *, K00959098 *, US00096455*), China, Yunnan, Szemao .

Twining herb; stems 1.5–6 m long, with thinly distributed, shortly appressed trichomes, flowering branches 1.7–2 mm diam. Stipules narrowly ovate, falcate, 4.5–15 by 2–4 mm, apex acute, subglabrous, especially inside. Leaves: petiole ± round in transverse section, adaxially shallowly grooved, 2–15 cm long, basally and apically pulvinate, and often twisted/curved at lower pulvinus, shortly sericeous with simple trichomes; stipel- lae ovate, 1.3–6 by 0.7–1 mm, with pedicelled glands basally inside, outside hairy, (sub)glabrous inside; blade deeply 3- (or 5-)lobate, ovate, 4–21 by 6–22 cm, 0.7–0.9 times longer than wide, papyraceous when dry, symmetric, base deeply emarginate, margin indistinctly serrate, flat, teeth bent towards apex, ending in gland, apices acuminate, upper surface dark green, lower surface lighter green, both sides with short appressed trichomes especially on venation, glabrescent, sometimes an occasional long sharp hair present; basally 5-nerved with be- tween nerves abaxially roof-like domatia, lobes penninerved, with 12 or 13 veins per side in midlobe (counting from junction), looped and closed near margin, higher nerves reticulate, sidelobes with two major veins of which lower short; midlobe ovate to elliptic, 9–14.8 by 2.2–3.8 cm (length measured from connec- tion with petiole), symmetric, side lobes asymmetrically ovate, 8.3–13.4 by 2.5–4.6 cm. Inflorescence solitary, axillary (see note 3); peduncle 3.3–19.5 cm long, subglabrous, halfway often a small(er), often caducous leaf leaving persistent stipules and axillary bud; involucral bracts sessile, subequal, ovate, 3-lobed, 4–6.8 by 2–6.5 cm, margin entire but with glandular trichomes (appearing as serrate), inside subglabrous, outside sparsely hairy, 5- or 7-nerved, with 3 acute lobes, basally with several stalked glands; basally each bract with 2 bracteoles, obliquely ovate, to 10 by 4 mm long, with at attachment inside several stalked glands, apex acute. Pistillate part basally with two pale green bracts, ovate, lower one 3-lobed, c. 6 by 15 mm, the subopposite higher bract c. 10 by 5 mm, apex 2-lobed; pistillate flowers 3, cymose, on short, 1.5–2 mm long pedicels; sepals 8–12, in two rows, ovate-triangular, c. 1.5 by 0.5 mm, com- pletely short hairy, margin with long glandular, hairy trichomes with a c. 1.4 mm long stalk, and c. 0.3 mm long gland; ovary ovoid, slightly 3-lobed, c. 1.3 by 1.3 mm, densely short hairy, 3-locular; style 8–11.8 mm long, cylindrical, hairy, apex slightly widened into stigma, stigma somewhat 3-lobed, becoming convex discoid later. Staminate part only present in young inflorescences, caducous, on a c. 2.5 mm pedicel above the group of pistillate flowers, sturdy, broadening towards apex, with a few short appressed trichomes; on top 4 bracts in two rows, outer 2 larger, ovate, c. 6 by 4.5, apex a bit erose, completely slightly hairy with short appressed trichomes; staminate flowers 7–10, light green, pedicel up to 10 mm long, with abscission zone in upper third, slightly hairy; sepals 4 or 5, ovate, 2–3.3 by 1.5–1.8 mm, recurved but upper bent inwards, apex acute with apical gland, both sides shortly sparsely hairy; androphore c. 2 mm long, free filaments 0.5–0.7 mm long, anthers c. 25, ellipsoid, c. 1 by 0.7 mm, with 1 theca larger than the other; staminodial bractlets below flowers, at one side of flowers, in tight groups with anther-like parts parallel. Fruits: pedicels elongating to 18 mm long, longest with the median flower; sepals elongating to 25 by 1.5 mm, becoming ± pectinate as glandular trichomes elongate to c. 5 mm long, the glandular tips disappear, the sharp trichomes covering the sepals become stiff and elongate up to c. 1.5 mm long; stigma in fruit 2 × broader than style, disc-shaped. Fruits 3-lobed, c. 13 by 6 mm, densely shortly hairy; columella c. 4.5 mm high, top widened into 3 wings of c. 2 mm long. Seeds 3–5 mm diam, white and reddish brown marmorated.

Distribution — China (Yunnan), Myanmar (Tavoy = Dawei District), Laos (?), Thailand (South-Western, South-Eastern, Peninsular), Malesia: Sumatra, Java.

Habitat & Ecology — Evergreen forest, edge of primary for- est, secondary forest with bamboo; once recorded from lime- stone.Altitude: 90–1200 m. Flowering: May,August, November, December; fruiting: January, May, July, August, October to December. For pollination information see Armbruster et al. (2011).

Vernacular names ― Java: Areuj kakapasan ( Smith 1910; Bakhuizen van den Brink 2346), Aroi Kekapasan ( Miquel 1859) or Aroy Kakapassang ( Blume 1825) (Sundanese); Oedoe lada, Patjahan ( Smith 1910).

Notes ― 1. The best fruiting material (no flowering material) that could be attributed to Blume (and not Herb. Blume, which are generally specimens from a later date) has been selected as lectotype.

2. On Java the leaf lobes of many specimens are more slender than in other areas; normally the species is found at altitudes up to 800 m, but Koorders 35784 from Java is from 1200 m and has much smaller leaves.

3. The inflorescence seems to develop axillary, with then in the lower third to halfway there is a leaf (often smaller than the other leaves, generally caducous), which shows that it is in fact a side branch with a terminal inflorescence. The whole side branch is here considered to be the peduncle.

Figures

Fig. 1 Dalechampia bidentata Blume. a. Habit with two leaves (lower two) and an inflorescence of which only two bracts visible, at base of bracts bracteoles; b. inflorescence with bracts removed, showing still two bracteoles,staminate part visible surrounded by bracts and with glandular staminodial bractlets in front, in background pistillate part; d. opening staminate flower; d. anthers;e. pistillate part of same inflorescence with three bracts visible around the 3-flowered cyme; f. pistillate flower; g. pistillate flower with calyx removed; h. fruit with extended sepals and extended glandular trichomes (‘side branches’) covered with stinging trichomes; i. columella (a–g: Middleton, Suddee & Hemrat 1607; h, i: Van Harreveld HT 4422; all L). — Drawn by Esmée Winkel.