The genus Allium L. has been traditionally circumscribed in the tribe Allieae under the Liliaceae (Bentham & Hooker, 1883; Vvedenskii, 1935; Lawrence, 1951; Xu & Kamelin, 2000), but recently several authors have placed this genus in its own family Alliaceae (Dahlgren et al., 1985; Takhtajan, 1997; Rahn, 1998; Friesen et al., 2000). The genus is characterized by the presence of bulbs enclosed in membranous (sometimes becoming fibrous) tunics, free or almost free tepals, and often a subgynobasic style (Friesen et al., 2006). Most taxa produce remarkable amounts of cystein sulphoxides causing the well-known characteristic odor and taste (Friesen et al., 2006). Over 700 species of this genus are widely distributed in the northern hemisphere, especially in the temperate regions of Eurasia, and also growing in southern hemisphere such as Africa (Hutchinson, 1959; Ohwi, 1984; Rahn, 1998; Takhtajan, 1997; Xu & Kamelin, 2000). The genus has a main center of diversity in southwest and central Asia with a smaller secondary area of diversification in North America. About 29 taxa, excluding cultivated species, are known from northeastern China and Korea (Vvedenskii, 1935; Ohwi, 1984; Xu & Kamelin, 2000; Choi et al., 2004b). More recently, two new endemic species from South Korea, A. linearifolium H. J. Choi & B. U. Oh and A. koreanum H. J. Choi & B. U. Oh, have been described (Choi & Oh, 2003; Choi et al., 2004a).

Table I Comparison of species of A llium Sect. R hizirideum in northeastern China and Korea. (Measurements based on at least 30 specimens.)
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Allium sect. Rhizirideum G. Don ex Koch is characterized by well-developed thick rhizomes, membranous bulb tunics, more or less fleshy leaves, scapes drooping before flowering, pink to lilac perianths, and usually flowering from late June to September. This section has about 15 taxa, and a geographic range from Europe to Asia. Among these, eight taxa are known to be distributed in northeast Asia, including far eastern Russia, northeastern China, Korea, and Japan (Vvedenskii, 1935; Ohwi, 1984; Xu & Kamelin, 2000; Choi et al., 2004b). Based on our study about Allium material from northeastern China and Korea, four taxa have been recognized, including A. senescens L. var. senescens, A. senescens L. var. minus S. Yu, W. Lee & S. Lee, A. spirale Willd., and an undescribed species.

In this study, we describe and illustrate a new species of Allium sect. Rhizirideum from northeastern China. Also, A. senescens var. minus from this section, restricted to Korea, is erected to species rank. These two species, A. pseudosenescens H. J. Choi & B. U. Oh and A. minus (S. Yu, W. Lee & S. Lee) H. J. Choi & B. U. Oh, are readily distinguished from their relatives, A. senescens and A. spirale, based on morphological and cytological characters.

Allium pseudosenescens H. J. Choi & B. U. Oh, sp. nov. Type: China. Heilongjiang: Tahe, Talin Linchang, open slope of rocky area, N 52°19´52.9˝, E 124°37´45.4˝, 374 m, 31 Jul 2008 (fl), H. J. Choi 080119 (holotype: KH; isotypes: CBU, KH). (Figs. 1, 2)

Haec species Allio senescenti similis, sed ab eo pedicellis gracilioribus, perianthio pallide roseo, tepalis ovarioque angustioribus, anthere flavescentibus, et filamentis subulatis interdum dentatis differt.

Perennial herbs. Rhizomes well-developed and elongated, horizontal and branched, 16–52.8 mm long. Bulbs clustered, cylindric-conical, without bulblets, 12–20 mm in diam.; tunics membranous, smooth, white. Leaves 4–10; leaf sheaths slightly exposed over ground, 4–8 cm high, non-striped; leaf blades ascending, slightly tortuous, linear, flat, fleshy, 23–45 cm long, 5–15 mm wide, solid and with 2-rowed vascular bundles in cross-section, sessile at base, obtuse to rounded at apex. Scapes sometimes lateral from the bulbs, not slender, subterete to rhomboid, drooping before flowering, solid in cross-section, 25.8–70 cm long, 3–5.5 mm wide. Inflorescences umbellate, subglobose, 30–60 mm high, 40–60 mm wide, without bulblets, 31–120 flowered; pedicels terete, equal in length, 10–32 mm long, thinner than the scapes, slender; bracts 4.8–6.5 mm long. Flowers bisexual; perianth radially spreading, pale pink; inner tepals longer than outer ones, elliptical, obtuse at apex, 6–6.8 mm long, 2.5–3 mm wide; outer tepals ovate-elliptical, obtuse at apex, 4.5–5.5 mm long, 2–2.7 mm wide; filaments long exserted, subulate, 7–11 mm long, entire or 2-toothed (middle of inner ones) at margin; anthers elliptical, yellowish, 1.9–2.1 mm long; ovary obovoid, reddish, without hood-like projections at base, 3.2–4 mm long, 2.2–2.6 mm wide, ovules 2 per locule; style terete, exserted; stigma smooth. Capsules cordiform, trigonous, 4.5–5.5 mm long, 4.5–5.6 mm wide. Seeds oval, semi-circular in cross-section, 3–3.5 mm long, 2.2–2.4 mm wide. Chromosome number 2n = 4x = 32.

Distribution and ecology.—The distribution of A. pseudosenescens is somewhat limited. So far, it has been found only in the northern region of Heilongjiang, China, in open meadows and on arid slopes. Because of its restricted distribution, this new species is thought to be endemic to China.

Phenology.—Flowering from July to September.

Etymology.—The specific epithet is given considering its similarity with A. senescens.

Additional specimens examined. CHINA. Heilongjiang: Tahe, Xifeng Linchang, 1 Aug 2008, H. J. Choi 080278 (KH); Dashinganryeong, Aug 1954, Linxingzu 07577 (PE).

Allium pseudosenescens had been identified as A. senescens in various Chinese herbaria (Choi & Oh, pers. obs.), but the former is easily distinguished by its slender pedicels, pale pink perianths, narrower tepals and ovaries, yellowish anthers, and sometimes toothed subulate filaments (Table I; Figs. 1, 2 and 3A–D). Allium senescens is widely distributed from Europe to central Korea. In addition, phylogenetic analysis of nrITS sequence data indicates that A. pseudosenescens is genetically distinct from the other northeastern Chinese and Korean species in sect. Rhizirideum (Choi, 2009).

Fig. 1
figure 1

Allium pseudosenescens. A. Habit. B. Somatic chromosomes. C. Cross-section of scape (vb: vascular bundles, dark area: fiber). D. Perianth. E. Tepal and filament arrangement. F. Pistil. G. Capsule. H. Seed. (A–F from H. J. Choi 080199, KH; G, H from H. J. Choi 080278, KH.)

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Fig. 2
figure 2

Allium pseudosenescens. A.Allium in habitat. B. Inflorescence. C. Underground structure. D. Tepal and filament arrangement. E. Perianth. F. Pistil. G. Capsule. H. Seed. (A–F from H. J. Choi 080199, KH; G, H from H. J. Choi 080278, KH.)

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Fig. 3
figure 3

Comparative illustrations and photographs of the inflorescence, cross-section of scape (vb: vascular bundles, dark area: fiber), tepal and filament arrangement, and somatic chromosomes of Allium sect. Rhizirideum in northeastern China and Korea. A–D. A. senescens (2n = 4x = 32). E–H. A. minus (2n = 2x = 16). I–L. A. spirale (2n = 2x = 16). (A–C from H. J. Choi 070001, KH; D–F from H. J. Choi 080063, KH; G–I from Jilin 23-060902-007, CBU.)

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Allium minus (S. Yu, W. Lee & S. Lee) H. J. Choi & B. U. Oh, comb. et stat. nov. Basionym: Allium senescens L. var. minus S. Yu, W. Lee & S. Lee, J. Korean Pl. Taxon. 11: 32. 1981 [“minor”]. Type: Korea. Gangwon-do: Inje-gun, mesic pine-forest underground ca. 400 m toward a hill of Wolhaksam-ri, Yoo 5101 (holotype: WKUH; isotypes: KWNU, SNU-n.v., JNU-n.v.). (Fig. 3D–F)

Perennial herbs. Rhizomes well-developed and elongated, oblique and branched, 4.3–8.6 mm long. Bulbs clustered, cylindric-conical, without bulblets, 4.3–8.6 mm in diam.; tunics membranous, smooth, white. Leaves 5–7; leaf sheaths slightly exposed over ground, 2.8–4 cm high, non-striped; leaf blades ascending, spirally tortuous, flat, fleshy, linear, 11.4–24.5 cm long, 2.8–4.5 mm wide, solid and with 2-rowed vascular bundles in cross-section, sessile at base, obtuse to rounded at apex. Scapes central from bulbs, not slender, subterete, drooping before flowering, solid in cross-section, 11.7–20.5 cm long, 1.5–1.6 mm wide. Inflorescence umbellate, hemiglobose, 15–25.4 mm high, 25–33 mm wide, without bulblets, 32–85 flowered; pedicels terete, equal in length, 6–8 mm long, thinner than the scapes; bracts 2.7–4.8 mm long. Flowers bisexual; perianth radially spreading, pale pink, inner tepals longer than outer ones, elliptical, obtuse at apex, 3.5–4.7 mm long, 1–1.8 mm wide; outer tepals ovate-oblong, obtuse at apex, 3.4–4.1 mm long, 0.8–1.2 mm wide; filaments non-exserted, 3.8–4.8 mm long, entire at margin; anthers elliptical, reddish, 1.1–1.3 mm long; ovary obovoid, reddish, without hood-like projections at base, 2–2.3 mm long, 1.7–1.9 mm wide, ovules 2 per locule; style terete, exserted; stigma smooth. Capsules cordiform, trigonous, 3.5–3.7 mm long, 3.6–4 mm wide. Seeds oval, semi-circular in cross-section, 2–2.2 mm long, 1.3–1.5 mm wide. Chromosome number 2n = 2x = 16.

Local name.—Jom-bu-chu (Yu et al., 1981).

Distribution and ecology.—Endemic to central Korea (Gangwon-do; Gyeonggi-do), in habitat of mesic forests and dry slopes. This is a very rare species in the field, but it is widely cultivated as an edible plant named “Yeong-yang-bu-chu” mainly in Gyeonggi-do, Korea.

Phenology.— Flowering from May to July.

Additional specimens examined. KOREA. Gangwon-do: Inje-gun, 26 May 1979, B. S. Gil 0022887 (KWNU); Inje-gun, W. T. Lee 0022892 (KWNU); Inje-gun, Wolhaksam-ri, 18 May 2008, H. J. Choi 080063 (KH). Gyeonggi-do: Yangju-si, Yuyang-dong, Bulguk-san, 20 June 2007, H. J. Choi 070086 (KH).

This species had been recognized as a variety of Allium senescens (Yu et al., 1981). However, this Korean endemic taxon is a biologically distinct species. It is remarkably distinguished from the other northeastern Chinese and Korean members of sect. Rhizirideum (e.g., A. senescens, A. spirale and A. pseudosenescens) in having much narrower and shorter leaf blades and scapes, smaller floral organs, non-exserted filaments and earlier flowering season from May to late July (Table I; Fig. 3). Moreover, this is a diploid (2n = 2x = 16) taxon along with A. spirale, whereas A. senescens and A. pseudosenescens are tetraploids (2n = 4x = 32) (Table I; Fig. 3). Considering these major differences we propose the rank of species for this taxon as more appropriate than that of variety.

The northeastern Chinese and Korean Allium species in sect. Rhizirideum can be distinguished with the following key.

Key to the species of Allium sect. Rhizirideum in northeastern China and Korea

  • 1. Leaf sheaths buried under ground; leaf blades leathery, lustrous; scapes flattened-winged in cross-section; perianths campanulate, pinkish violet; inner tepals ovate-elliptical; inner filaments entire at margin

    A. spirale

  • 1. Leaf sheaths exposed above ground; leaf blades fleshy, glaucous; scapes subterete to rhomboid in cross-section; perianths radially spreading, reddish pink or pale pink; inner tepals elliptical; inner filaments entire or toothed at margin.

    • 2. Leaf blades 2.8–4.5 mm wide; scapes subterete in cross-section, 11.7–20.5 mm long; inner tepals 3.5–4.7 mm long, 1–1.8 mm wide; outer tepals 3.4–4 mm long, 0.8–1.2 mm wide; filaments non-exserted, 3.8–4.8 mm long; capsules 3.5–3.7 mm long, 3.6–4 mm wide; seeds 2–2.2 mm long, 1.3–1.5 mm wide; flowering from May to July (2n = 2x = 16)

      A. minus

    • 2. Leaf blades 3.8–15 mm wide; scapes subterete to rhomboid in cross-section, 23.4–70 mm long; inner tepals 6–7 mm long, 2.5–3.5 mm wide; outer tepals 4.5–5.5 mm long, 2–2.7 mm wide; filaments exserted, 6.2–11.0 mm long; capsules 4.5–5.6 mm long, 4.5–5.8 mm wide; seeds 3–3.8 mm long, 2.2–2.6 mm wide; flowering from July to October (2n = 4x = 32).

      • 3. Rhizomes oblique; pedicels not slender; perianths reddish pink; inner filaments narrowly triangular, entire at margin; inner tepals 3–3.4 mm wide; anthers reddish; ovaries 3–3.5 mm wide

        A. senescens

      • 3. Rhizomes horizontal; pedicels slender; perianths pale pink; inner filaments subulate, entire or 2-toothed at margin; inner tepals 2.5–3 mm wide; anthers yellowish; ovaries 2.2–2.6 mm wide

        A. pseudosenescens