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FOC | Family List | FOC Vol. 5 | Aristolochiaceae

2. Asarum Linnaeus, Sp. Pl. 1: 422. 1753.

细辛属 xi xin shu

Asiasarum F. Maekawa; Geotaenium F. Maekawa; Heterotropa C. Morren & Decaisne; Japonasarum Nakai.

Herbs perennial; annual growth modules consisting of 2-4 cataphylls, 1 or 2 foliage leaves, and a terminal flower. Rhizomes short and vertical or long and horizontal; rhizomes and roots often pungently aromatic. Stems herbaceous. Foliage leaves solitary or paired on each growth module (when paired appearing opposite), usually long petiolate, often cordate or sagittate, margin entire. Flowers terminal, solitary (rarely paired). Perianth uniseriate, actinomorphic (rarely slightly zygomorphic). Calyx adnate to ovary to varying degrees; sepals either connate beyond attachment to ovary and forming a tube or free and forming false tube above ovary; tube cupular, urceolate, campanulate, funnelform, or cylindric, often ribbed or tessellate on adaxial surface, constricted or open at throat (orifice), throat with or without narrowly projected, contiguous shelf of tissue (orifice ring); lobes 3, erect, spreading, or reflexed. Stamens 12 in 2 series, rarely with 3 staminodes; filaments long to almost absent; anthers extrorse. Ovary inferior or half-inferior, 6-loculed; carpels fully connate. Styles 6, free or united into column, apex entire or 2-lobed; stigma terminal or lateral. Fruit a fleshy or spongy capsule, splitting irregularly when ripe. Seeds convex dorsally, plane or grooved ventrally, with fleshy funicle at base. 2n = 12, 24, 26.

About 90 species: mostly in SE Asia, a few species in North America, one species endemic to Europe; 39 species (34 endemic) in China.

No material of Asarum sprengeri Pampanini (Nuovo Giorn. Bot. Ital., n.s., 18: 113. 1911) has been seen. It is possibly related to A. chinense. The unpublished name “Asarum campaniforme” is in use among horticulturalists for a plant of apparently Chinese origin, which has large bell-shaped flowers with whitish interior of the calyx tube and almost black calyx lobes.

1 Sepals free or connate beyond attachment to ovary, without distinct tube or only with very short one; sepals abaxially pubescent; stamen filaments usually longer than anthers; styles connate into column, apex entire or notched; stigmas terminal; ovary inferior.   (2)
+ Sepals connate beyond attachment to ovary, forming variously shaped tube; sepals abaxially glabrous, rarely pubescent; stamen filaments very short or nearly lacking; styles free or rarely united at base, apex often notched or 2-cleft; stigmas lateral, rarely terminal; ovary superior or inferior.   (12)
2 (1) Sepals connate beyond attachment to ovary, forming a calyx tube.   (3)
+ Sepals free beyond attachment to ovary (sometimes connivent but not connate).   (7)
3 (2) Calyx actinomorphic, lobes triangular, apically acute; styles slender; stigmas not radiating downward; leaves paired on flowering shoots, solitary on nonflowering shoots.   (4)
+ Calyx slightly zygomorphic, lobes triangular-orbicular to rounded-ovate, apically rounded; styles short and thick, stigmas radiating downward, subdecurrent; leaves paired on flowering and nonflowering shoots.   (5)
4 (3) Stamens 6-9; flowers (including lobes) less than 1 cm; calyx lobes erect.   6 A. debile
+ Stamens 12; flowers (including lobes) more than 1.5 cm; calyx lobes spreading.   7 A. caudigerellum
5 (3) Leaf blade narrowly ovate or ovate-lanceolate, apex acuminate; anthers 0.8-1.2 mm; connectives less than 0.3 mm.   11 A. epigynum
+ Leaf blade ovate, ovate-cordate, or broadly ovate, apex acute or obtuse; anthers 2-3 mm; connectives 0.7-1.3 mm.   (6)
6 (5) Leaf blade 13-22 cm; stamen filaments 0.4-0.7 mm.   9 A. yunnanense
+ Leaf blade 5-10 cm; stamen filaments less than 0.4 mm.   10 A. geophilum
7 (2) Calyx lobes erect or spreading, caudate to acuminate, rarely acute.   (8)
+ Calyx lobes reflexed and appressed to false tube, rounded, obtuse, or acute.   (10)
8 (7) Shoots elongate, internodes 2-6 cm.   3 A. cardiophyllum
+ Shoots condensed, internodes less than 2 cm.   (9)
9 (8) Calyx lobe abruptly caudate at apex, tail 10-25 mm; style lobes entire, stigmas terminal.   1 A. caudigerum
+ Calyx lobe gradually caudate at apex, tail 2-4 mm; style lobes notched, stigmas at base of notch.   2 A. renicordatum
10 (7) Plants densely covered with long white hairs, hairs turning black when dried.   4 A. pulchellum
+ Plants only sparingly to moderately pubescent, hairs remaining white when dried.   (11)
11 (10) Leaves paired on vegetative shoots; stamens and styles slightly exserted.   5 A. caulescens
+ Leaves solitary on vegetative shoots; stamens and styles included.   8 A. himalaicum
12 (1) Stamen filaments longer than anthers; leaves paired on vegetative shoots; styles short; calyx tube without laminate ring.   (13)
+ Stamen filaments usually very short; leaves solitary on vegetative shoots; styles long; calyx tube usually with laminate ring at throat.   (14)
13 (12) Calyx lobes erect or spreading, never reflexed at anthesis; leaf blade apex shortly acuminate or acute, adaxially sparsely pubescent.   12 A. sieboldii
+ Calyx lobes reflexed at anthesis; leaf blade apex acute or obtuse, adaxially shortly pubescent along veins.   13 A. heterotropoides
14 (12) Styles entire at apex, rarely slightly 2-cleft; stigmas terminal or subterminal.   (15)
+ Styles conspicuously 2-fid or notched at apex; stigmas lateral.   (18)
15 (14) Calyx tube strongly constricted at throat, adaxial surface tessellate (sometimes only inconspicuously transversely corrugate), orifice ring present.   (16)
+ Calyx tube slightly or not constricted at throat, adaxial surface longitudinally rugose, orifice ring absent.   (17)
16 (15) Rhizomes long spreading, horizontal; leaf blade elliptic or ovate, rarely cordate, apex acuminate; calyx tube gradually dilated above orifice forming short neck, then divided into lobes.   14 A. chinense
+ Rhizomes short, vertical; leaf blade cordate or ovate-cordate, apex acute to obtuse; calyx tube without neck, divided immediately into lobes.   15 A. ichangense
17 (15) Leaf blade ovate-cordate to ovate, both surfaces glabrous, adaxially shiny; lateral calyx lobes erect or spreading; connectives obtuse; styles connate, apex with 6, erect, slightly 2-cleft arms.   16 A. hongkongense
+ Leaf blade triangular-ovate to narrowly ovate, pubescent, adaxially not shiny; lateral calyx lobes reflexed; connectives awl-shaped; styles 6, free, apex entire.   17 A. fukienense
18 (14) Calyx tube inner surface tessellate.   (19)
+ Calyx tube inner surface with longitudinal ridges, sometimes with crossbars, but not tessellate.   (29)
19 (18) Calyx tube slightly or not at all constricted at throat, orifice ring narrow (ca. 1 mm or less wide) or absent.   (20)
+ Calyx tube strongly constricted at throat, orifice ring broad and evident (2.5-5 mm wide).   (24)
20 (19) Calyx tube broadly cupular or subglobose, orifice ca. 15 mm in diam., ring absent.   18 A. splendens
+ Calyx tube subcylindric to campanulate, orifice 4-8 mm in diam., ring absent or present.   (21)
21 (20) Calyx lobes adaxially pubescent, spreading, orifice ring absent.   22 A. taipingshanianum
+ Calyx lobes adaxially glabrous (sometimes papillose), erect or slightly spreading, orifice ring present.   (22)
22 (21) Leaf blade broadly cordate to reniform-cordate, length and width subequal; calyx lobes adaxially smooth, without papillate area.   19 A. forbesii
+ Leaf blade triangular-oblong to triangular-ovate, length greater than width; calyx lobes adaxially papillose or rugose at base.   (23)
23 (22) Leaves 6-17 × 5-16 cm; petiole 8-25 cm; calyx lobes 1.5-2 × 2-2.5 cm, with rounded papillose area at base (Sichuan).   21 A. bashanense
+ Leaves 3-7 × 2.3-2.9 cm; petiole 5-8 cm; calyx lobes ca. 0.4 × 0.5 cm, irregularly thickened, glandular-rugose at base (Taiwan).   20 A. crassisepalum
24 (19) Stigmas elongate, linear-oblong or oblong-ovoid; style apex hooked; calyx lobe margins undulate.   (25)
+ Stigmas not elongate, rounded to ovoid; style apex not hooked; calyx lobe margins hardly undulate.   (26)
25 (24) Leaf blade triangular-ovate, abaxially with purple veins; petiole streaked reddish brown; stamens oblong; connectives thick and notched at apex; stigmas linear-oblong; style apex distinctly hooked.   23 A. macranthum
+ Leaf blade ovate-cordate or narrowly ovate, abaxially with green veins; petiole uniformly green; stamens triangular; connectives obtuse or acute, entire at apex; stigma oblong-ovoid; style apex obscurely hooked.   24 A. crispulatum
26 (24) Flower 2-2.5 cm in diam., calyx tube urceolate, 1-1.2 × 1.1-1.4 cm, orifice ring ca. 1 mm wide.   28 A. porphyronotum
+ Flowers more than 3 cm in diam.; calyx tube subcylindric or conic, 1.5-2 × 0.7-1.5 cm, orifice ring 1.5-3 mm wide.   (27)
27 (26) Petiole 4-7 cm, pilose at maturity; calyx 2.5-3 cm in diam.   27 A. chengkouense
+ Petiole 10-21 cm, glabrous at maturity; calyx 3-6 cm in diam.   (28)
28 (27) Connectives slightly extended beyond anthers, apex awl-shaped; calyx lobes broadly ovate, 2-3 × 3-4 cm.   25 A. delavayi
+ Connectives not extended beyond anthers, apex rounded; calyx lobes subrotund, ca. 1 × 2 cm.   26 A. hypogynum
29 (18) Calyx tube abruptly swollen toward middle or above, forming barrel-shaped dilated zone.   (30)
+ Calyx tube cylindric or enlarged gradually, but lacking prominent dilated zone.   (32)
30 (29) Calyx lobes with pinkish, triangular papillate area at base; tube above abruptly swollen into broad disk which is longitudinally ridged, orifice very constricted, ring broad.   29 A. inflatum
+ Calyx lobes with white or yellowish, circular or semicircular pulvinate area at base; tube with robust dilated zone at middle inner surface without ridges, orifice ring absent.   (31)
31 (30) Calyx tube swollen forming girdle-like ring near middle, lobes with papillate transverse rows at base, orifice ca. 1 cm in diam.; peduncle 1-5 cm.   30 A. maximum
+ Calyx tube swollen with girdle-like ring near apex, lobes without papillate transverse rows, orifice small, less than 1 cm in diam.; peduncle 2-9.5 cm.   31 A. insigne
32 (29) Calyx tube and abaxial surface of leaf blade densely yellowish brown pubescent; peduncle recurved, pubescent.   37 A. wulingense
+ Calyx tube and leaf blade abaxially glabrous or only veins with hairs; peduncle erect, subglabrous.   (33)
33 (32) Orifice ring absent or inconspicuous (rarely formed by papillae, but not as a contiguous ring); calyx tube 2-5 cm, slightly or not at all constricted at throat.   (34)
+ Orifice ring present, conspicuous, 2-3 mm wide; calyx tube 1-2.5 cm, slightly to strongly constricted at throat.   (36)
34 (33) Calyx 2.5-3 cm wide; tube 2-2.5 cm, lobes with minute pulvinate area (ca. 2 mm in diam.) or scattered papillae at base, papillae not forming ribs in tube; petiole 2.5-7.5 cm.   32 A. nanchuanense
+ Calyx 4-5 cm wide; tube 3-5 cm, lobes usually with prominent papillate area at base, over 5 mm in diam., papillae extending in longitudinal rows from base to form ribs in tube; petiole 6-23 cm.   (35)
35 (34) Calyx tube erect and symmetric, throat not constricted, rarely with papillate ring; leaf blade triangular-ovate to elliptic-ovate, apex acute to shortly acuminate; rhizomes short, vertical.   38 A. magnificum
+ Calyx tube often inclined to one side, slightly asymmetric, throat slightly constricted; leaf blade narrowly ovate, triangular-ovate, or oblong-hastate, apex long acuminate; rhizomes elongated, horizontal.   39 A. petelotii
36 (33) Calyx lobes not conspicuously pubescent adaxially.   (37)
+ Calyx lobes densely pubescent adaxially.   (38)
37 (36) Plants robust, with short rhizomes and thick, fleshy roots; leaf blade narrowly or broadly ovate to triangular-ovate, 11-14 cm wide; flowers usually paired; stamen connectives awl-shaped.   33 A. sagittarioides
+ Plants slender, with long rhizomes and fibrous roots; leaf blade oblong-ovate or narrowly elliptic-ovate, 5-8 cm wide; flowers solitary; stamen connectives ligulate.   34 A. longerhizomatosum
38 (36) Calyx tube cylindric, 0.9-1.5 cm in diam.; leaf blade adaxially uniformly green.   36 A. tongjiangense
+ Calyx tube lantern-shaped, slightly swollen at middle, ca. 2 cm in diam.; leaf blade adaxially faintly white spotted.   35 A. nobilissimum

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