Millettia puerarioides Prain (1897: 358)

Song, Zhuqiu, Pan, Bo, Zhang, Ting, Tan, Yunhong, Zhang, Yongsheng, Yang, Zuwei & Xu, Dongxian, 2021, Millettia puerarioides Prain (Fabaceae: Millettieae), a species with cauliflorous inflorescences newly recorded from China, Phytotaxa 507 (2), pp. 183-190 : 185

Millettia puerarioides Prain (1897: 358) $叶崖ÿ

Type:— MYANMAR. Tenasserim: Choungya , 1219 m, 30 March 1877, Geo Gallatly 531 (lectotype K000848744!, designated here). Pegu: Tonkyeghat, Nakawachoung, Sulpiz Kurz 1765 (remaining syntype K000848745!) .

Evergreen small trees or woody climbers; stems less branched at the lower position, up to 4–8 m tall and 10 cm in diameter at breast height; bark grayish brown, densely covered with whitish lenticels; young shoots yellow puberulent and glabrescent. Leaves imparipinnate, alternate; leaflets 5–9, opposite; rachis 15.3–23.7 cm long, including petiole 4.5–11.5 cm long; terminal leaflet largest, 17–34 × 5.6–12.5 cm, symmetric, cuneate at base; the lowest leaflet smallest, 6.2–13 × 3.2–8 cm, slightly asymmetric, cuneate to rounded at base; all leaflets long caudate at apex, apex 1.0– 3.5 cm long; stipules ovate, pubescent, 2–3 × 1.0– 1.2 mm; stipels absent; leaflets papery, narrow ovate to lanceolate, with dense appressed hairs above and subglabrescent, with persistent dense appressed silky hairs below; lower side conspicuously glaucous; secondary veins 5–9 pairs, looped near margin; petiolules 0.6–1.2 cm long. Pseudoracemes rami- and caulinascent, pendulous, 6–52 cm long, singular or several clustered at old stem; brachyblasts at lower part of inflorescence wart-like, ca. 2 mm long in flowering, up to 12 mm long in fruiting, with 5–10 flower buds but only a few developing into fruits; bracts subtending brachyblasts scarious, ovate-triangular, ca. 0.8 × 0.5 mm, inserted at the base of brachyblast; floral bracts, similar to the bracts subtending brachyblasts in texture, shape and size, inserted at the base of pedicel; bracteoles 2, ovate, inserted at the base of calyx; pedicels short, 2–3 mm long; rachis, pedicels, bracts and bracteoles densely covered with ferruginous hairs. Flower 1.2–1.3 cm long; calyx campanulate, indistinctly lobed, densely covered with ferruginous hairs outside; petals purplish red to pink; standard suborbicular, 9–10 × 8–10 mm, emarginate at the apex, two auricles at base, densely covered with ferruginous hairs on the outer surface; wing oblong, ca. 8 × 3 mm, obtuse at apex, with a 3 mm long claw, glabrous on both surfaces; keel elliptic, ca. 8 × 4 mm, obtuse at apex, with a 3 mm long claw, densely ferruginous on the outer surface at apex; stamens 10, monadelphous, 1.0– 1.1 cm long, with small openings (fenestrae) at both sides at base; pistil 1.0– 1.1 cm long; floral disk tubular; ovary sessile, densely sericeous, with about 3 ovules; style curved; stigma terminal, small, capitate. Pods compressed at first and becoming inflated with time, slightly to deeply constricted between seeds, densely ferruginous tomentose on the outer surface, 4–13 × 1.7–2.3× 1.6–1.8 cm, with a distinct beak at apex; fruiting pedicel ca. 3–4 mm long; valves leathery. Seeds 1–3 (mostly 1), large, 28–31 × 14–15 × 13–14 mm; seed coat dark red; hilum central, ca. 1 mm in diameter. Flowering from April to August, and fruiting from June to next January.

Notes: — Millettia puerarioides was previously recorded as a woody climber ( Prain 1897; Dunn 1912; Kress et al. 2003), but the voucher specimens and observations from Chinese populations showed that it has the capacity to grow into small trees under evergreen forests. We also noticed that this species was described with ultimately glabrous pods in previous literature ( Prain 1897; Brandis 1906; Dunn 1912), which is not consistent with Chinese specimens as well as our field observations in China. Chinese material has pods that are densely covered with persistent ferruginous tomentose hairs on the outer surface ( Fig. 2H ). Moreover, we found that the pseudoraceme of this taxon includes one bract inserted at the base of each brachyblast, one floral bract inserted at the base of each pedicel, and two bracteoles inserted at the base of each calyx ( Fig. 2C ). Critical observations on the bracts in the inflorescence may be useful for understanding the evolution of the complicated genus Millettia .

Figures

FIGURE 2. Millettia puerarioides Prain from Yingjiang County, Yunnan Province, China. A. Trunk with numerous inflorescences; B. Abaxial surface of leaflet; C. Part of inflorescences, showing one bract at the base of each brachyblast, one floral bract at the base of each pedicel, and two bracteoles at the base of calyx; D. Leaves and inflorescences; E. Branchlet with a raminascent inflorescence; F. Part of inflorescence; G. Dissection of a flower (from left to right: calyx, standard, wings, keels, monadelphous stamens and ovary), scale bar = 1 cm; H. Pods, scale bar = 1 cm; I. Trunk with numerous infructescences.