FABACEAE TRIB. EUCHRESTEAE (Nakai) Ohashi, J. Jap. Bot. 48: 229. [Draft]

山豆根族 shan dou gen zu

Dalbergieae Subtrib. Euchrestinae Nakai, J. Jap. Bot. 16: 24. 1940.

SUN Hang, Kai Larsen

Shrubs or perennial herbs. Leaves with pulvini, imparipinnate, estipellate; stipules caducous, small. Inflorescences racemes. Standard attenuate to stalk, wings rather like keel. Calyx campanulate to tubular. Stamens diadelphous, standard and stamens free; anthers heteromorphic. Ovary often 2-ovuled; style fine, glabrous. Pods bluish purple, indehiscent.

WEN Hequn. 1998. Trib. Euchresteae. pp. 383–388. In: Cui Hongbin, ed. Fl. Reipubl. Popularis Sin. 42(2).

EUCHRESTA Bennett, Pl. Jav. Rar. 148. 1838.

山豆根属 shan dou gen shu

Shrubs. Leaves alternate, imparipinnate; leaflets 3–7, opposite, estipellate. Flowers solitary along inflorescence rachis; bract persistent, small; bractlets absent. Calyx campanulate to tubular, very oblique and gibbous at back, caducous in fruit; teeth 5. Corolla much exserted; standard suberect, narrow, slightly longer than wings and keel; wings oblong, obtuse, slightly falcate, free, claw very long; keel rather like the wings, scarcely cohering at apex. Stamens 10, diadelphous (9+1), vexillary free, remainder slightly connate; anthers small, versatile. Ovary stipitate, 1- or 2-ovuled; style filiform, incurved; stigma capitate, small. Pod stipitate, ovoid or ellipsoid, drupe-like, indehiscent, 1-seeded. Seeds exalbuminous, without strophiole, seed coat white, membranous. X = 9.

About four species: Indonesia (Java), Japan, Philippines, and SE China to northern India; four species in China.

1a.     Calyx tubular, longer than 1 cm, upper part broader, lower part narrower ...........  4. E. tubulosa

1b.     Calyx cup-shaped or campanulate, shorter than 1 cm.

2a.    Leaflets often 3(–5); calyx cup-shaped, 2–5 mm; standard apically not concave  1. E. japonica

2b.    Leaflets (3–)5–7(–9); calyx obliquely campanulate, ca. 9 mm; standard apically retuse.

3a.     Leaflets to 9, elliptic-lanceolate or narrowly elliptic, tapering at apex ......  2. E. formosana

3b.     Leaflets (3–)5, often obovate or broadly elliptic, apex cuspidate, abaxially appressed lanulose         3. E. horsfieldii

1. Euchresta japonica J. D. Hooker ex Regel, Gartenflora 14: 321. 1865.

山豆根 shan dou gen

Euchresta trifoliata Merrill.

Climbing shrubs, nearly not branched. Stems often with adventitious roots. Leaves with 3 leaflets; petiole 4–5.5 cm, appressed pubescent, adaxially with a conspicuous groove; terminal petiolule 0.5–1.3 cm, lateral petiolule nearly absent; leaflets abaxially pale green, adaxially dark green, elliptic, 8–9.5 Χ 3–5 cm, thickly papery, abaxially appressed pubescent, adaxially glabrous, corrugated when dried, lateral veins very inconspicuous, base broadly cuneate, apex acuminate to obtuse. Racemes 6–10.5 cm; peduncle 3–5.5 cm; pedicel 0.5–0.7 cm, both surfaces appressed pubescent; bractlet fine, subulate. Calyx cup-shaped, 3–5 Χ 4–6 mm, outside and inside appressed pubescent; lobes bluntly triangular. Corolla white; standard oblong, ca. 1 cm Χ 2–3 mm, outside sparsely appressed pubescent at base, apex obtuse or spatulate, sepal stalk linear, slightly reflexed, ca. 2 mm; wings elliptic, ca. 9 Χ 2–3 mm, apex obtuse, stalk linear, ca. 2.5 mm Χ less than 1 mm wide; keel upper connate; sepal elliptic, ca. 1 cm Χ 3.5 mm, with small auricle at base, sepal stalk ca. 2 mm. Ovary prolate or linear, ca. 5 mm, stalk ca. 4 mm; style ca. 3 mm. Infructescence ca. 8 cm. Pods dark, ellipsoid, 1.2–1.7 Χ ca. 1.1 cm, glabrous, apex obtuse, mucronulate; pedicel ca. 1 cm, with podogyne ca. 4 cm, glabrous.

Valleys or mountain slopes, dense forests; 800–1400 m. Guangdong, Guangxi, Guizhou, Hunan, Jiangxi, Sichuan, Zhejiang [Japan].

2. Euchresta formosana (Hayata) Ohwi, J. Jap. Bot. 12: 659. 1936.

台湾山豆根 tai wan shan dou gen

Euchresta horsfieldii Bennett var. formosana Hayata, Icon. Pl. Formosan. 3: 81. 1913.

Shrubs. Branches flexuose, very fine fulvous pubescent at apex. Leaflets (3–)5–7(–9), narrowly elliptic to elliptic-lanceolate, papery to membranous, base cuneate, apex acuminate; terminal leaflets ca. 9 Χ 3.5 cm, petiolule ca. 1.2 cm; lateral leaflets 6–8 Χ 2.5–2.8 cm, petiolule ca. 2 mm. Racemes 10–15 cm; flowers congested; peduncle brown appressed pubescent; pedicel 2–6 mm, bract lanceolate, small, ca. 2 mm. Flowers purple-white. Calyx campanulate, ca. 8 Χ 6–7 mm at tip, both surfaces very shortly pubescent; teeth short, blunt. Standard spatulate, ca. 1.5 cm Χ 5.5 mm, tapering to base, both surfaces pubescent at base, without stalk; wings suboblong, ca. 9 Χ 3 mm, base auriculate, sepal stalk linear, ca. 6 mm Χ less than 1 mm wide, glabrous; keel oblong, ca. 8 Χ 4 mm, base auriculate, apex blunt, stalk linear, ca. 5.5 mm Χ less than 1 mm wide; filament equal to keel, outside pubescent at base. Anther short. Ovary compressed, stipitate, ca. 7 mm, glabrous. Pods glossy, dark at apex, oval, ca. 2.2 cm, podogyne ca. 1 mm at base; 1-seeded. Fl. Aug, fr. Feb of next year.

Taiwan [Japan (Ryukyu), Philippines].

3. Euchresta horsfieldii (Leschenault) Bennett, Pl. Jav. Rar. 148. 1838.

伏毛山豆根 hu mao shan dou gen

Andira horsfieldii Leschenault, Ann. Mus. Paris 16: 481. 1810, [‘Harsfieldii’]; E. strigillosa C. Y. Wu.

Shrubs, ca. 45 cm tall. Branches and branchlets glabrous, longitudinally striate. Leaves with 3–5 leaflets; petiole 8–12 cm; leaflets thickly papery, abaxially densely adpressed lanuginose, adaxially glabrous; midvein slightly convex abaxially, slightly impressed adaxially, lateral veins 5 or 6 pairs, inconspicuous on both surfaces; terminal leaflet broadly elliptic or obovate-elliptic, 11–17.5 Χ 6–8 cm, base cuneate, apex cuspidate, petiolule ca. 1.3 cm; lateral leaflets nearly sessile, opposite, elliptic, 9–15 Χ 4.5–8 cm, base cuneate to suborbicular, apex cuspidate. Racemes to 13–21 cm, densely adpressed hairy; peduncle ca. 10 cm; bract inconspicuous, ca. 1 mm. Calyx broadly campanulate, 5–6 Χ 5–6 mm, 5-lobed at tip, obliquely nearly truncate, with very fine appressed hairs. Corolla easily deciduous, nodding, milky, ca. 1.5 cm; standard rectangular, ca. 1.1 cm Χ 4 mm, apex obtuse and retuse, base small auriculate at both sides, conduplicate, reflexed, with stalk ca. 5 Χ 1 mm; wings rectangular, ca. 1 cm Χ 3 mm, apex obtuse, base small auriculate at both sides, upper lateral larger, stalk ca. 4 mm Χ less than 1 mm wide; keel obovate-oblong, apex rounded, base small auriculate at both sides, upper lateral larger, upper margin connate, ca. 1.1 cm Χ up to 4 mm wide, sepal stalk to 4 mm Χ less than 1 mm wide. Stamen tube ca. 1.4 cm. Ovary oblong, ca. 6 mm, attenuate to stalk at base, ca. 5 mm, 1-ovuled; style ca. 4 mm; stigma punctiform, small. Pod bright black, ellipsoid, ca. 2 Χ 1.3 cm, indehiscent, stalk 6–8 mm, podogyne ca. 1.2 cm, with one joint between both.

Evergreen broad-leaved forests in limestone areas; 1000–1400 m. Yunnan (Hekou, Maguan, Malipo), Xizang (Medog) [Bhutan, Indonesia, Nepal, Thailand, Vietnam].

4. Euchresta tubulosa Dunn, J. Linn. Soc., Bot. 35: 492. 1903.

管萼山豆根 guan e shan dou gen

Shrubs. Leaves with 3–7 leaflets; petiole 6–7 cm; terminal petiolule 0.6–1 cm, lateral petiolules ca. 2 mm; leaflets elliptic or obovate-elliptic, terminal leaflet subequal to lateral leaflets, 8–10.5 Χ 3.5–4.5 cm, papery, abaxially appressed fulvous pubescent, adaxially glabrous, midvein slightly convex abaxially, flat or slightly impressed adaxially, lateral veins 5 or 6 pairs, inconspicuous, base cuneate to rounded, apex cuspidate to blunt. Racemes terminal, 8–16 cm; peduncle ca. 4 cm; pedicel ca. 4 mm, appressed fulvous pubescent. Flowers 2–2.2 cm. Calyx tubular, lower ones narrow, (4–5 mm or) 9–10 mm, ca. 2 mm wide, with bursicule at base; upper ones expanded to cup-shaped, ca. 6 mm; lobes bluntly triangular, 1–1.5 mm. Standard reflexed and curved, ca. 1.5 cm, apex blunt or retuse, upper half ca. 5 mm wide, downward attenuate to sepal stalk, base ca. 2 mm wide; wings sepal oblong, ca. 8.5 Χ 3.5 mm, base truncate, without auricles, apex obtuse; sepal straight on one side and arcuate on other side, sepal stalk ca. 7 Χ 1 mm; keel oblong, lower part free, upper part connate, apex obtuse, sepal ca. 7 Χ 3 mm, with small projection at base, sepal stalk ca. 6 mm Χ less than 1 mm wide. Stamens tube ca. 1.2 mm. Ovary linear, ca. 5.5 mm, gynophore ca. 1.3 cm; style linear, ca. 4 mm. Pods dark brown, ellipsoid, 1.5–1.8 cm Χ ca. 8 mm, both ends obtuse, apex with a very short mucro; infructescence ca. 10 cm, podogyne ca. 1.4 cm. Fl. May–Jun(–Jul), fr. Jul–Sep.

* 300–1700 m. Guangxi,  NW Hubei, Hunan, Sichuan, Yunnan (Mengla).

1a.. Leaflets elliptic or obovate-elliptic, terminal leaflet subequal to lateral leaflet, 8–10.5 Χ 3.5–4.5 cm; inflorescence ca. 8 cm ...................................................................................  4a. var. tubulosa

1b.. Leaflets obovate or elliptic, terminal leaflet larger than lateral leaflets; inflorescence 14–16 cm.

2a.. Leaflets obovate; calyx tube longer below, 9–10 mm ........................  4b. var. longiracemosa

2b.. Leaflets elliptic; calyx tube shorter below, 4–5 mm ..................................  4c. var. brevituba

4a. Euchresta tubulosa var. tubulosa

管萼山豆根 (原变种) guan e shan dou gen (yuan bian zhong)

Leaflets elliptic or obovate-elliptic, terminal leaflet subequal to lateral leaflet, 8–10.5 Χ 3.5–4.5 cm. Inflorescence ca. 8 cm.

* 300–1700 m. NW Hubei, Hunan, Sichuan.

4b. Euchresta tubulosa var. longiracemosa (S. Lee & H. Q. Wen) C. Chen, Acta Phytotax. Sin. 30(1): 50. 1992.

长序山豆根  chang xu shan dou gen

Euchresta longiracemosa S. Lee & H. Q. Wen, Guihaia 4(2): 139. 1984.

Leaves with 3–5 leaflets; petiole 7–10.5 cm; leaflets broadly elliptic to obovate, apex shortly cuspidate; terminal leaflet 13.5–14 Χ 9–10 cm, petiolule 1–1.5 cm; lateral leaflets 10.5–13 Χ ca. 7 cm, base cuneate to broadly so, petiolule 3–5 mm. Racemes 14–16 cm. Fl. Apr–Jun.

* Forests on limestone mountain slopes; ca. 1200 m. Guangxi.

4c. Euchresta tubulosa var. brevituba C. Chen, Acta Phytotax. Sin. 30(1): 50. 1992.

短萼山豆根  duan e shan dou gen

Inflorescence ca. 14.5 cm. Calyx tube short below, ca. 5 mm. Fl. Jun.

* 700–800 m. Yunnan (Mengla).