Millettia pulchra(Benth.) Kurz var. munnarensis, a new variety of Millettia Wight & Arn. is described and illustrated from the Western Ghats of India. This variety differs from all other 7 varieties of M. pulchra in having larger flowers and 8-10 seeded pods. A detailed description, illustration and distribution map with a key for the identification of all the varieties of M. pulchra are provided.

Keywords: millettia, fabaceae, New variety, Western Ghats, India

The genus Millettia Wight & Arn. (Fabaceae-papilionoideae) is one of the largest genera of the tribe Millettieae with more than 100 species.¹ The genus is mainly distributed in the tropics of Africa and Asia. Wight & Arnott² established the genus upon two climbing shrubs, M. rubiginosa and M. splendens, both are endemic to the southern Western Ghats of India. As per Sanjappa,³ the genus in India is represented by 13 species, 1 variety and one forma, and most of them are widely distributed in China, South Asia and Indochina. While exploring the legume flora of Kerala state of south India, the authors collected some interesting specimens of a tree widely planted in the margins of tea plantations in Munnar, a high altitude hill station in central Kerala. The tree resembles Millettia pulchra (Benth.) Kurz in general appearance, but differs in having larger flowers and 8-10 -seeded pods. M. pulchra was originally described by Kurz⁴ from northeast India based on Wallich cataloge no. 5630 pp. Later, Prain⁵ added a new variety - tomentosa to the species from Manipur (northeast India). While revising the genus Millettia, Dunn⁶ added 3 more varieties from China, namely, chinensis, microphylla and yunnanensis and a forma (M. pulchra var. pulchra f. laxior) from Khasia hills of northeast India. During the revision of Chinese Millettia, Wei⁷ raised f. laxior in to the status of a variety and also recognized another new variety from China, i.e. var. parvifolia. Thus, M. pulchra presently comprises 7 varieties and are chiefly confined to three countries, viz. China, Myanmar and India⁸ (Map 1). In India, the species is represented by three varieties, namely, pulchra, laxior and tomentosa and all are restricted to the northeastern states. The presently collected specimen of M. pulchra from Munnar is strikingly different from all other varieties so far recognized due to its larger flowers and 8-10 -seeded pod.Subsequent detailed specimen study, consultation of relevant literature^6-9 and herbarium specimens at CAL and MH and virtual herbaria of major herbaria of the world have confirmed that the plant is distinct from all other known varieties of M. pulchra and it is described here as a new variety. This taxon might have been introduced as a shade tree in the tea plantations of Munnar during the British rule and is now naturalized around Munnar and adjacent hill stations. A detailed description, illustration, photographs, distribution map and key for identification of all the varieties of M. pulchra are provided for the easy identification of the plant in the field. Millettia pulchra (Benth.) Kurz var. munnarensis A.P. Balan & S.V. Predeep, var. nov. (Figures 1 & 2).

Figure 1 Millettia pulchra (Benth.) Kurz var. munnarensis A.P. Balan & S.V. Predeep, var. nov. A. Habit; B. Pod; C. Pod-split opened; D. Mature pod before dehiscence; E. Pod after dehiscence.

Figure 2 Millettia pulchra (Benth.) Kurz var. munnarensis A.P. Balan & S.V. Predeep , var. nov. A. Habit; B. Bract; C. Bracteole; D. Calyx; E. Standard; F. Wings; G. Keels; H. Stamens; I. Pistil; J. Pod; K. Seed.

Map 1 Distribution of different varieties of Millettia pulchra (Benth.) Kurz.

Millettia pulchra var. munnarensis var. nov. is allied to M. pulchra in its general appearance and vegetative characters. But the 2.8 cm long flowers and 16-20 cm long, 8-10 -seeded pods are strikingly distinct characters from that of all other varieties of Millettia pulchra viz., var. chinensis, laxior, microphylla, parviflora, pulchra, tomentosa and yunnanensis, having 1-1.2 cm long flowers and c. 12 cm long, 3-5 -seeded pods.

Type

India, Kerala, Idukki District, Munnar, 10°08′ N, 77°05′ E, at ± 1800 m, 24 December 2009, S.V. Predeep and Anoop P. Balan 20986 (Holotype: MH; Isotypes: CALI).

Para type

India, Kerala, Idukki District, Silent Valley, 10° 05′ N, 77o 10′ E, at ± 1950 m, 28 September 2016, Anoop P. Balan 20983 (MH).

Small trees, 3-5 m high; bark of young branchlets lenticellate. Stipules 3-4 mm long, ovate-lanceolate, sparsely pubescent outside, caducous; stipels 2-3 mm long, linear, pubescent, caducous. Leaves 26-30 cm long, imparipinnate; petioles 3-4.5 cm long, tawny villous; rachis 12-21 cm long, sparsely tawny villous; leaflets 13-21, opposite; petiolules 3-4 mm long, tawny villous; lamina 5-8 × 2-3.5 cm, stiff chartaceous; lateral leaflets elliptic-oblong, sub truncate-rounded and slightly asymmetric at base, shortly acuminate and obtuse-retuse at apex, glabrous above, sparsely sericeous below along the midvein, glaucous beneath; terminal leaflet elliptic, attenuate and symmetric at base; secondary veins 8-10 pairs. Pseudoracemes 5-8 (-10) cm long, shorter than leaves, axillary, lax; rachis velvety-pubescent; peduncle 1.5-5 cm long, pubescent. Flowers 2.8 cm long, purple, 2-3 fascicled on each node of the rachis; pedicels 0.4-0.5 cm long, pubescent. Bracts and bracteoles ca 3 × 1 mm, linear-lanceolate, pubescent outside. Calyx velvety-pubescent; tube 6-7 mm long, campanulate; lobes 1.5 × 1.5 mm, deltoid. Corolla much exserted; standard 21 × 21 mm, suborbicular, retuse at apex, silky pubescent outside, claw ca 7 mm long; wings 18 × 8 mm, obovate-oblong, shortly auricled at base, claw 10 mm long; keels 18 x 9 mm, oblong, glabrous, claw 8 mm long. Stamens 10, monadelphous; sheath 12-14 mm long; filaments 5-6 mm long, equal; anthers 1.25 × 1 mm, ovoid, uniform. Ovary subsessile, 12 × 1 mm, linear, densely pubescent, 6-10 -ovuled; style 8 mm long, incurved, glabrous; stigma capitate. Pods 16-20 × 2-2.5 cm, strap-shaped with a curved beak, sessile, glabrous when matured, valves subleathary, coiled after dehiscence. Seeds 8-10, 1 × 0.8 cm, ellipsoid, dark brown, funicle fleshy.

1. Phenology: Flowering from December to February; fruiting from March to September.
2. Habitat: Shade tree in the margins of tea plantations at 1700-2000 m elevation.
3. Distribution: Widely planted as shade tree in roadsides and tea plantations in Devikulam Taluk of Idukki district, Kerala state.
4. Etymology: The variety is named after the type locality, Munnar, Idukki district of Kerala state, southern India.

Key to the varieties of M. pulchra

1. Flowers c. 1.2 cm long; Pods 6-12 cm long, 1-5 -seeded ……………..….….. 2
2. Flowers 2.8 cm long; Pods 16-20 cm long, 8-10 -seeded ……………...... var. munnarensis
3. Calyx lobes deltoid …………………………………..………………..………. 3
4. Calyx lobes acuminate ……………………………………………………..…. 7
5. Leaflets 2-10 cm long, abaxially hairy throughout ……………………..……. 4
6. Leaflets c. 1.8 cm long, abaxially pilose along midvein and margin ………… var. parviflora
7. Leaflets and branchlets pubescent or sparsely pilose or villous …….……..…. 5
8.  Leaflets and branchlets tomentose ……………………………………..…….. var. tomentosa
9. Leaflets acute-acuminate at apex, adaxially hairy ……………………………. 6
10. Leaflets obtuse at apex, adaxially glabrous ………………………………... var. microphylla
11. Leaflets c. 6 cm long, acuminate at apex; Pods 1–3 –seeded ……...................… var. pulchra
12. Leaflets 6.5-10 cm long, acute at apex; Pods3–5 –seeded …………….............…. var. laxior
13. Leaflets <6 cm long, elliptic, symmetric at base …………………..………….. var. chinensis
14. Leaflets 6-10 cm long, oblong, conspicuously asymmetric at base ………. var. yunnanensis

The authors are grateful to Kerala State Council for Science, Technology and Environment, Thiruvananthapuram for the project ‘Studies on the Legume Flora of Kerala State’; authorities of S.V.R. N.S.S. College, Vazhoor for facilities; the curators of BM, E, K, LINN, M, S etc. for the virtual images of type specimens and CAL & MH, for permitting to consult specimens. We are grateful to Dr. G.P. Lewis, Royal Botanic Gardens, Kew, London, for his critical comments on the identity of the plant.

Authors declare there is no conflict of interest.

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