[2.13.3] Viola sect. Plagiostigma subsect. Bulbosae

Viola subsect. Bulbosae Marcussen, subsect. nov.

—Type: Viola bulbosa Maxim.

Description.—Rhizome annual, growing from underground bulbil. Lateral stems present: underground stolons, usually leafless but with scattered nodes. Stipules outer stipules adnate, inner stipules free, pale, linear-lanceolate, remotely fimbriate. Lamina oblong-ovate, suborbicular or reniform, base cuneate or narrowly cordate, apex rounded or acute, margin crenulate. Corolla white. Sepals lanceolate to broadly lanceolate; appendages short (c. 0.8 mm), rounded. Lateral petals bearded or not; bottom petal shorter than the other petals (7–8 mm), apex rounded; spur short (1.2–1.7 mm) and saccate. Style at apex margined and bilobate.

Diagnostic characters.—Rhizome vertical, growing from deep-buried bulbils.

Ploidy and accepted chromosome counts.—4x; 2n = 24.

Age.—Crown node age unknown, stem node age 13.5 (12.2–14.0) Ma [28].

Included species.—2. 

Viola bulbosa Maxim., 

Viola  tuberifera Franch.>efloraindia

Distribution.—Eastern Himalaya and central China.

Discussion.—Section Plagiostigma subsect. Bulbosae comprises two species, Viola bulbosa and V. tuberifera [77,281]. The species are characterised by having small underground bulbs, a unique feature in Viola. The bulb is composed of 4–8 fleshy petiole bases along a condensed axial portion which apically elongates into the annual aerial stem and laterally produces underground, leafless stolons with cleistogamous flowers. The species were included in subsect. Patellares by both Becker [1] and Wang [76], as grex Adnatae and sect. Adnatae, respectively.

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