Helonias kawanoi (Koidz.) Tanaka (1998a: 109)

Tanaka, Noriyuki, 2019, Taxonomy, evolution and phylogeography of the genus Helonias (Melanthiaceae) revisited, Phytotaxa 390 (1), pp. 448-450 : 448-450

7. Helonias kawanoi (Koidz.) Tanaka (1998a: 109) ( Figs. 16 , 17 ).

≡ Sugerokia kawanoi Koidzumi (1937: 46) . Type:— JAPAN. Loochoo [Ryûkyû, Okinawa Pref. ]. Insula Irumti [Iriomote I.], ad Urautigawa, 6 Jun. 1923, G. Koidzumi s.n. (Holotype: KYO n.v.; photo in TNS!). ≡ Heloniopsis kawanoi Koidzumi (1937: 46) . ≡ Hexonix kawanoi (Koidz.) Wang & Tang (1949: 113) .

– Heloniopsis orientalis (Thunb.) Tanaka var. yakusimensis auct. non (Masam.) Ohwi: Masamune (1957: 103), p.p.

– Heloniopsis umbellata auct. non Baker: Hatusima (1971: 786; 1975: 786); Hatusima & Amano (1977: 198).

– Heloniopsis kawanoana Koidz. in Sakaguchi (1924: 86), nom. inval.

Japanese name:―Ko-shôjôbakama ( Koidzumi 1937), Okinawa-shôjôbakama ( Sakaguchi 1924).

Description:―Rhizome subcylindrical, to 7 mm long, to 3 mm in diam. Roots filiform, ca. 0.5 mm in diam., ramose, white. Leaves many, narrowly oblanceolate or spatulate, 2–7 cm long, 0.5–1 cm wide, base narrowly cuneate, margin entire or occasionally slightly minutely undulate at margin, apex acute or short acuminate with apiculus at 0.8–1.5 mm long, light green, subglossy (when young) or dull, thin in texture, midvein and parallel veins usually slightly raised adaxially, persistent for 1–2 years. Flowering stem upright: peduncle usually 6–12 cm long at anthesis, elongating to 18.5 cm long (incl. plants in cultivation) in fruit, slender, 0.7–2.5 mm in diam. in middle, ribbed; scale-like leaves on peduncle 4–17(–24) (excl. basal ones), narrowly lanceolate or subulate, to 2 cm long, to 4 mm wide, acute or acuminate, membranous or subherbaceous, basal ones herbaceous; inflorescence (sub)umbellate or sometimes (sub)racemose; pedicels 3–12 mm long (incl. in fruit), ribbed, usually pale pink, bracteate at base. Flowers 1 to 4(–9) (incl. plants in cultivation), funnelform, 7.5–14 mm across, usually nodding, faintly fragrant, protogynous. Tepals 6, obliquely expanded, narrowly oblong-elliptic or (oblong-)oblanceolate, 4–8.4 mm long, 1.5–3 mm wide, apex acute to obtuse, sometimes recurved distally, veins (3 or) 5, white or pink, adaxially slightly cannaliculate toward base, proximal submaginal portions slightly raised, margin slightly revolute, little or slightly imbricate with adjoining tepals proximally, nectary on adaxial base slightly concave; abaxial base slightly gibbous; base of tepal affixed to receptacle (apex of pedicel) for ca. 0.5–0.6 mm in length. Stamens 6, subequaling tepals, obliquely expanded; filaments filiform, straight, 2–5.5 mm long, white or pink; anthers adaxially basifixed, slightly extrorse, ovoid, 0.5–1.6 mm long, base sagittate, bilocular with trace of apical confluence between thecae, white, pale cream or pale lilac; pollen white or pale cream. Pistil 1, 5–7.8 mm long, usually slightly exceeding, sometimes equaling or slightly shorter than tepals; ovary subglobose or obovoid, 1.3–3 mm long, 1.8–3.2 mm across, slightly trigonous, trisulcate, apex emarginate-concave, pale green, dull pink or dirty dark reddish brown; style erect, terete, often slightly broadened above, 2.1–5.2 mm long, white or pink; stigma discoid or slightly trilobed, 0.7–2 mm across, white, sometimes slightly tinged purple. Capsules obpyramidal (obcordate laterally), 3.5–4.5 mm long, 3.5–5 mm across, trifid or tripartite, apex emarginate-depressed in center; lobes subconic, ascending, apex obtuse. Seeds many, linear-fusiform, 2.5–3.3 mm long, 0.2–0.3 mm wide, testa whitish, proximally caudate-sublinear, distally acicular; body of seed narrowly oblong, 1–1.4 mm long, 0.2(–0.3) mm wide, brown.

Additional specimens examined (see also Tanaka 1998a):― JAPAN. Kyûshû. Kagoshima Pref., Amami-ôshima Isl.: Yuwandake, 20 May 1951, T. Amano 6500 (RYU-25059). Okinawa. Okinawa Pref., Miyako Isl. : 9 August 1894, T. Ito 1202 (TNS-60738). Okinawa Isl. : Kunigami, Aha, Tanaga-Gumui, elev. 100 m, 24 June 1955, fr., S. Hatusima 18309 (L-1455529*, TI). Iriomote Isl.: 26 October 1973, fr., M. Furuse 4414 (MAK-141694, RYU-17010); near Nakaragawa Riv., 12 August 1894, T. Ito 1458 (TNS-60736, -60737); Gozadake, 250 m, 26 December 1963, fr., T. Yamazaki (TI, RYU-27147). Ishigaki Isl.: Omoto-dake, August 1922, fl., S. Sakaguchi 31 (MAK-138905).

Distribution:―SW Japan, Nansei Isl. (incl. Ryûkyû Isl.). Kagoshima Pref.: Amami-ôshima, and Tokunoshima Isl.. Okinawa Pref. : Okinawa, Miyako, Ishigaki, and Iriomote Isl. ( Fig. 29 -Ka).

Habitat:―Shady or semishady moist mossy rocks along streams in forests at elevations ca. 80–400 m.

Conservation status:―Assessed by the Environment Agency of Japan (2000) as VU on the basis of the criterion E in IUCN (1994). Deforestation and road construction are regarded as threats to the species.

Flowering:―Usually (late June–)August–November(–January). Sometimes also to February or even to March under cultivation.

Ripening:―Usually October–December(–February). Sometimes to June.

Remarks:― Helonias kawanoi is a small, highly specialized plant with small, somewhat thin leaves, 1 to few flowers ( Fig. 16A–C ) blooming in late summer to autumn (even in winter in cultivation in Tokyo), and bracteate pedicels and smaller (shorter) seeds. In many temperate vernal species, such as H. bullata ( Fig. 1A ), H. orientalis ( Fig. 1B ) and H. thibetica , newly formed flower buds remain dormant during cold weather ( Fig. 2 ). In contrast, in H. kawanoi such dormancy appears to have been (nearly) lost, since flowering is principally in autumn ( Fig. 2 ). This feature may have been acquired as an adaptation to warm climates. Helonias kawanoi shares some character states with H. umbellata . It often has an umbel of obconic or funnelform, white or pink flowers ( Fig. 16A, B ) like H. umbellata ( Fig. 21A–C ).

Figures

FIGURE 1. Buds and their sprouting in Helonias. A. H. bullata (material Bu-1; photo on 5 April 2013). B. H. orientalis (O-3; 15 November 2014). C, D. H. thibetica (T-1; C on 19 February 2014, D on 2 March 2014). Flower buds or fresh flowering stem designated by F, leaf buds or sprouting leaves by L, rosulate leaves developed in previous years by R. In Fig. C, two of leaves developed in the preceding year marked with single white circle (dot); two of leaves developed the year before last marked with paired white circles (dots). Photo A by Jim Fowler at site of “Bu-1” in South Carolina; B–D by the author at Hachioji, Tokyo.

FIGURE 2. Diagram of phenology of rosette leaves and flowering stems (scapes) in Helonias. Phenological transition of rosette leaves (L) and flowering stem (F) in their lifetime (from bud formation to death) is schematized.Approximate magnitude of growth rate of two organs is expressed by line or shape of ellipse or lance (expanded portion). State of organs showing static, increasing or decreasing growth rate is represented respectively by line, or by expanding or narrowing (closing) portion of an ellipse or lance. Broken line represents period during which older leaves die, although their death is usually concentrated in growing season (April to July or August). In H. bullata, for example, leaf bud (see L-row) is initially formed in summer of year 0, it stays dormant until coming spring, and then develops rapidly in spring to summer (expanded open portion) of year 1. Mature leaves wither in growing season of following year (broken line in year 2). Flower bud of H. bullata (see F-row) is initially formed in fresh rosette (in L-row) in summer of year 1; like leaf bud it stays dormant until next spring, and then develops rapidly in spring (expanded shaded portion) of year 2. Flowering stem dies around summer of same year (closing shaded portion). Leaf bud (see L-row) of H. kawanoi, H. leucantha or H. umbellata after formed soon starts to sprout in late summer onwards (of year 0), although its growth appears more or less suppressed in subsequent cooler seasons (*). Phenological progression of flowering stem of H. kawanoi (F-row) tends to be lagged (**) when cultivated under lower temperature (in Tokyo) than in natural habitats.

FIGURE 16. Helonias kawanoi (material Ka-3). A–C; one and same plant. A. Flowering plants with sprouting fresh leaves (arrowed) (photo: 3 December 2014). B. Umbellate flowers (4 December 2014). C. Ascending flowers after anthesis (19 December 2014). D, E. Rosettes with sprouting leaves (arrowed) and flowering stems (D on 15 November 2014; E on 19 December 2014). All photos taken at Hachioji, Tokyo.

FIGURE 17. Helonias kawanoi (A, B, E: material Ka-3. C, D, F: material Ka-1). A. Young slightly open flower with anthers not yet dehiscent. Three frontal tepals removed. B. Closeup of densely papillulate stigma (st) of same flower as A. C. Flower with frontal tepal and stamen removed. D. Interior of partial flower. E. Vertical section of flower. F. Dehisced anther with apical confluence between thecae (arrowed), side view. IF; inner filament. OF; outer filament.

FIGURE 21. Helonias umbellata. A. Young slightly open flowers with protruding pistils (material U-1; photo on 3 March 1989). B. Flowering plant (U-2; 14 March 1989). C. Umbel (U-1; 30 March 1992). D. Plant with fresh leaves (light green) and leaves developed in preceding year (darker green) grown in greenhouse during winter (U-3; 14 March 2015). All photos at Hachioji, Tokyo.

FIGURE29.Distributionofsixspeciesbelongingtotwoseriesofsubsect.HeloniopsisinEAsia.B:Heloniasbreviscapa.Ka:H.kawanoi.Ko: H.koreana.L:H.leucantha.O:H.orientalis.U:H.umbellata.Ser.UmbellataecomprisesKa,LandU.Ser.HeloniopsisconsistsofB,KoandO.