Trichosanthes laceribractea Hayata

Duyfjes, B. E. E., Nuraliev, M. S., Luu, H. T., Huynh, N. T., Ngo, V. C., Kuznetsov, A. N. & Kuznetsova, S. P., 2016, Two new species and one new species record of Trichosanthes (Cucurbitaceae) from Vietnam, Blumea 61 (3), pp. 267-271 : 270-271

3. Trichosanthes laceribractea Hayata

Trichosanthes laceribractea Hayata (1911) 117; C. Jeffrey (1980) 40; H. Y. Liu (1993) 868 (‘ laceribracteata ’); Lu Q. Huang et al. (2011) 43. ― Type: Kawakami & Kobayashi 1589 ( TI TI0001071 ), Taiwan .

Perennial climber c. 10 (?) m long; leafy stem grooved on drying, young twigs, tendrils, petioles, and veins on lamina below reddish tinged, whole plant generally glabrous except the inflorescence, c. 3 mm diam; dioecious. Probract ovate-elliptic, c. 13 mm long, subentire. Tendrils 3-branched, one branch strongest, up to 20 cm long, point of branching 4.5‒6 cm from the base. Leaves: petiole 5‒6 cm long, c. 2 mm diam; lamina brown-green on drying, membranous, (3‒)5-lobed for c. 1/3, outer lobes much smaller, in outline subcircular, 13‒15 cm diam, glands 1–2, flat, 2‒3 mm diam, situated at c. 2 cm from the insertion of the petiole, cystoliths minute (leaf surface not scabrous), base deeply cordate, margin remotely sharp-dentate, apex of lobes abruptly acuminate; veins and veinlets flat above, little raised beneath, veins minutely hairy above and very sparsely so below. Male raceme without a solitary flower co-axillary; peduncle 7‒10 cm long, c. 3 mm diam; rachis not thickened, 4‒6 cm long, 2‒3 mm diam, 5‒10-flowered; bracts subpersistent, elliptic(-obovate), 4.5‒6 by 3‒3.5 cm, margin coarsely ± irregularly serrate-dentate 3‒5 mm deep, glands absent. Male flowers: seemingly glabrous but finely hairy on magnification, see note 4; pedicel 3‒4 mm long, persistent; receptacle tube narrow, cylindrical, 55‒60(‒90) mm long, at throat 6‒7 mm wide; sepals long-triangular, long-acute-acuminate, 18‒20 by c. 5 mm, margin remotely sharply few-dentate; petals white, broadly fan-shaped, c. 35 by 50‒55 mm, at apex broad and irregularly and coarsely or finely laciniate-dentate, 5‒15 mm deep; synandrium c. 10 by c. 6 mm, anthers two 2-thecous, one 1-thecous, filaments inserted towards the apex of the receptacle tube, each connective at apex with undulating sterile prolongation c. 5 mm long. Female flower, fruit, and seed not known in Vietnam.

Distribution ― SE China, Taiwan, S Vietnam (Kon Ka Kinh National Park).

Habitat & Ecology (in Vietnam) ― Disturbed forest; 900 m elevation; flowers in May.

Notes ― 1. Trichosanthes laceribractea is a new record for Vietnam, only known by the collection Nuraliev 1474 (Gia Lai Province, Mang Yang District , A Yun Municipality , Kon Ka Kinh National Park , 31 km WNW of K’Bang, N14°12'31" E108°19'00", 900 m elevation, 13 May 2016; L, MW) .

2. Trichosanthes laceribractea keys out in the key to the species of Indochina ( De Wilde & Duyfjes 2012) beside T. fissibracteata C.Y.Wu ex C.Y.Cheng & C.H.Yueh and T. tricuspidata Lour. The first, T. fissibracteata differs in having a linear probract 20‒30 mm long, entire leaf margin and deeply laciniate male bracts; T. tricuspidata is distinct in having a smaller probract 5(‒10) mm long and smaller blade glands, 0.5‒1 mm diam.

3. Trichosanthes laceribractea was described from Taiwan, and occurs rather widespread in SE China. The species was recorded for Vietnam by Jeffrey (1980) based on the collection Pételot 1084, but this collection was later on relegated to T. fissibracteata by De Wilde & Duyfjes (2012). As can be expected of a collection rather away from China, in the Vietnamese plant some differences can be noticed (seen on the colour photographs): reddish colour of young twigs, tendrils and veins on lamina below, and the presence of fleshy prolongations of the connectives (Fig. 4d). Furthermore, it can be mentioned that the male bracts are longer, 4.5‒6 cm long vs 3‒4 cm long in China. The petals are pure white.

4. The flower shows up as glabrous, but on magnification (Fig. 4d) it can be seen that the flower bud is minutely hairy outside throughout and that the tube inside is long hairy in the broadened part, the petals are long hairy near the throat and shorter hairy adaxially.

5. Flowering phenology (based on observations of the Vietnamese plant): The flower begins to open around 22.00 P.M., full flowering at least between 23.00 P.M. and 2.30 A.M., at 6.30 A.M. the flower is abscised.

During the night the open flowers are visited by numerous small flies of the family Phoridae .