Neustanthus Bentham, Pl. Jungh.
Creators: name: Egan, Ashley N.
name: Pan, Bo
Publisher: name: Zenodo
Year: 2015
Subjects: Biodiversity
Taxonomy
Plantae
Magnoliopsida
Fabales
Fabaceae
Neustanthus

description: Neustanthus Bentham, Pl. Jungh. 2: 234–235. 1852   
 Type species: — Neustanthus phaseoloides (Roxburgh) Bentham, Pl. Jungh. 2: 235. 1852.   
 Diagnosis: —Perennial herbaceous climber or creeper. Stems hirsute with spreading hairs. Leaves pinnately trifoliolate. Leaflets entire or lobed. Stipules basifixed, open and reflexed. Nodose (hereinafter refers to a highly compacted inflorescence branch or brachyblast; e.g. Figure 1P) pseudoracemes axillary, several flowers clustered at each node. Calyx 5-lobed, the lower lobe longer, the upper two connate from the middle. Corolla blue or purple or white with purple to pink stripe. Vexillum without callosities, apex slightly emarginate, base with incurved auricles. Vexillary stamen connate to the tube. Ovules many. Fruits subterete, valves twisting upon dehiscence. Seeds barrel-shaped to oblong-elliptic.   
 Description: —Perennial herbaceous climber or creeper. Stems slender but strong, fibrous, up to 10 m long, rooting at the nodes, pubescent with spreading hairs. Stipules basifixed, triangular to ovate, 4–12 mm × 2–3 mm, acuminate, deciduous or persistent. Leaves pinnately trifoliolate; petiole 3–12 cm long, somewhat pubescent with adpressed and spreading hairs; leaflets broadly ovate, rhomboid, or ovate-rhomboid, the terminal one broader and symmetrical, entire or lobed, 3–18 cm × 2–16 cm, margin entire or sinuate, lateral leaflets sometimes oblique, 3–14 cm × 3–12 cm, mucronate, leaflets adpressed pubescent above, more densely below, veins conspicuous below, strongly pubescent, 3 from the base, 5 pairs of primary lateral veins, opposite or not; petiolules 2–6 mm long with spreading hairs; stipels 3–10 mm long, linear to lanceolate, setaceous. Inflorescences solitary, axillary pseudoracemes, unbranched, (4–)10– 35(–45) cm long, nodose (with brachyblasts), flowering above the middle with 4 or more flowers per node; bracts subtending the nodes, 2–5 mm long, caducous; pedicels 2–6 mm, pubescent; bracteoles 2 per flower, lanceolate, 3–4 mm × 1–2 mm. Calyx 4–9 mm long, hirsute on the outside, the tube 3–5 mm long, 5-lobed, the upper 2 lobes fused along half of their length or more but not entirely fused, 2–4 mm long, lateral lobes obtuse to acute, 1.5–3 mm long, the lower lobe acute to lanceolate-acuminate or subulate, longer than the others, 3–6 mm long. Corolla bluish-purple or white suffused with purple, pink, or bluish-purple, vexillum obovate, often with green or yellow patch at the base, 10–23 mm × 8–18 mm, base with 2 incurved auricles, without callosities; wing petals obovate-oblong, bluish-purple or white suffused with bluish-purple, slightly longer than the keel, 9–20 mm × 3–6 mm, one side of base with rounded auricle, claw slender, 3–4 mm long, basal margin lobed; keel petals falcate, bluish-purple or white with blue, green or purple tip, 10–21 mm long, base truncate, clawed, the claw 4–6 mm long. Ovary linear, hirsute, 10–15 mm long with ca. 20 ovules; style glabrous, 4–10 mm long, curving upward; stigma terminal, globose. Stamens diadelphous, the vexillary stamen adherent near the middle to the staminal column in bud but becoming free with age, 10–21 mm long; anthers basifixed, alternating on long and short filaments. Fruits leguminous pods, subterete, grey to black, first adpressed hirsute, glabrescent, 5–12 cm × 3–5 mm, valves twisting upon dehiscence, with papery partitions between the seeds. Seeds 15–20 per fruit, barrel-shaped to oblong-elliptic, 2.5–4 mm × 2–3 mm, 1.5–2 mm thick; funicle short, deltoid; arils elongate.   
 Phenology: —Flowering and fruiting various, dependent upon locality (see Table 2 of van der Maesen 1985 for detailed information).   
 Distribution: —Native to southern, eastern, and Southeast Asia: Australia, Bangladesh, Bhutan, Brunei, Cambodia, China, India, Indonesia, Laos, Malaysia, Myanmar, N. Borneo, Nepal, New Guinea, Philippines, Singapore, Solomon Islands, Sri Lanka, Taiwan, Thailand, Vietnam. Introduced widely to other tropical areas.   
 Vernacular:—ΞṘḍƀ san lie ye ge (Chinese), thua sian pa (Thai), phak phit (Thai).   
 Discussion: — Neustanthus is phylogenetically close to Sinodolichos (Egan et al., in prep.; Cagle 2013), a genus of similar geographic distribution. Both genera are perennial, herbaceous climbers or creepers, with spreading hirsute hairs and basifixed stipules. Both have long, acuminate calyx lobes and linear, somewhat compressed, subterete fruit. However, they differ in their inflorescence structure, with Neustanthus having a pseudoraceme whereas Sinodolichos has a true raceme. Neustanthus has ca. 20 seeds per pod that are usually barrel-shaped whereas Sinodolichos has 3–10 seeds that are oblong. The most recent treatment of P. phaseoloides by van der Maesen (2002) recognized three varieties: var. phaseoloides, var. javanica, and var. subspicata. These taxa have been variably recognized at the species level (e.g. as Neustanthus javanicus by Bentham (1832)), varietal levels (e.g. van der Maesen, 1985, 1994, 2002), or in synonymy under P. phaseoloides. A comprehensive sampling coupled with morphometric and/or molecular genetic work will be necessary to determine the best level at which to recognize these taxa. Pending further investigation, we choose to continue with the current recognition of these taxa at the varietal level. Resurrected names and new combinations are presented below. For a full list of synonyms and a key to the varieties and descriptions thereof, see van der Maesen (1985).
description: Published as part of Egan, Ashley N. & Pan, Bo, 2015, Resolution of polyphyly in Pueraria (Leguminosae, Papilionoideae): The creation of two new genera, Haymondia and Toxicopueraria, the resurrection of Neustanthus, and a new combination in Teyleria, pp. 201-226 in Phytotaxa 218 (3) on pages 203-204, DOI: 10.11646/phytotaxa.218.3.1, http://zenodo.org/record/13636012