生活型

shrub

形態特徵

• Trunk to 5 m tall and 45 cm in diameter.
• Leaves simply pinnate, linear-oblong to elongated oblong, (1.1–) 1.3–1.6 (–1.8) m long, (20–) 24–30 (–37) cm broad, the topmost (1–) 3–4 (–6) leaflets generally reduced in sequence to approach in length the spine-like (to 1 cm long) and often pungent rachis-apex, and thus forming an emarginate apex of the compound leaf; the spine-bearing rachis-base (10–) 15–25 (–30) cm long, 6–10 mm in diameter, generally rounded transversely on both surfaces, bearing (5–) 7–11 (–14) spines along the upper portion of each lateral side; spines 2–3 mm long; leaflets (110–) 130–170 (–200) on each side of a rachis, lanceolato-linear, straight to slightly falcate, ending in a rigid, pungent point, basally constricted and then decurrent downward the rachis, thick-coriaceous and hard, margin generally slightly thickened and/or slightly revolute, the median ones (the largest in dimension) (12–) 14–17 (–20) cm long, (5–) 5.5–6.5 (–7) mm broad, and so aligned that form a 55–65 degree-angle with the rachis, when fresh dark green and lustrous above and lighter green and dull below whereas when dry sometimes somewhat discolored and then turning duller above, midvein concolorous with the leaf-surface where it is exposed; in both fresh and dry (and pressed) conditions the midvein slightly elevated or flattened above but consistently and persistently strongly elevated below; lower surface covered with long glandular hairs in flushing stage, often becoming glabrous with age.
• Male cone ovoid-cylindric, generally 45–55 cm long, when dry and closed 6–7 cm in diameter and when fresh and open 8–10 cm; male sporophylls narrowly obtriangular, the median ones generally 3.5–4.5 cm long, (1.2–) 1.4–1.6 (–1.8) cm broad and apically cuspidate with the apical extension 1–2.5 mm long. Female sporophylls heavily pale-yellowish-tomentose in pollination stage but with age the tomentum becoming deeper in color and sometimes falling off to show the orange surface of the mature sporophyll, spade-like; the upper sterile lamina pinnatifid, generally orbicular and smaller in pollination stage and becoming larger and horizontally elliptic when seeds mature, when bearing mature seeds generally 5.5–7 cm long (the projecting apical pinna and the tapering lamina-base not considered) and 8–11 cm broad, with the undivided central portion rhombic to broadly fusiform, 6–7 cm long, 2.5–3.5 cm broad; pinnae 14–18 on each side, the median ones 2.5–4 cm long, the upper ones shorter and gradating to the divisions on the apical pinna, the latter slightly broader than its subjacent pinnae, pinnatifid, generally slightly but definitely projecting outside the geometrized curve connecting the apical points of all lateral pinnae; the stalk of the sporophyll 5–17 cm long with the median ones the longest and the outermost the shortest, subrhombic transversely, 4.5–8 mm in diameter, bearing (1–)2(–3) ovules on each side of its upper portion; ovules densely yellowish-tomentose, generally ellipsoid-oblong and compressed, 10-13 mm long (incl. tomentum).
• Seeds generally narrowly obovate to narrowly elliptic, sometimes approaching oblong, compressed, (3.5–) 4–4.5 (–5) cm long, equatorially elliptic to oblong, 2.4–3.3 cm in long diameter, 1.8–2.5 cm in short diameter; generally heavily pruinose, often with remnant hairs; outer seed-coat orange-yellow to orange-red or even reddish when mature, becoming purplish-red and shrunken when dry, with diminutive horizontal wrinkles even when fresh; flesh thin, soft, pulpy; stone irregularly to coarsely rugosely sculptured, with a few corky ridges along each of its 2 lateral sides; looking mature in September of the current year.
• This species has long been identified as <i>Cycas taiwaniana</i>, a species described by Carruthers in 1893, since its first collection by Sasaki in 1920. Shen et al. (1994) found that the type of the name <i>C. taiwaniana</i> strongly in agreement with a cycad population-group present in Guangdong and a certain nearby regions but not in Taiwan, and that the population-group confined in Taitung represents a different species. Thus, the name <i>C. taiwanian</i>a refers only to the Guangdong cycad, and our Taitung cycad needs its own name. Early this century some workers on the flora of Guangdong referred the collections of the Guangdong cycad made in Guangdong to <i>C. taiwaniana</i>. This correct opinion is now widely followed by contemporary plant taxonomists stationed in mainland China (see Fu et al., 1978; among others). <i>Cycas taitungensis</i> is closely related to, but clearly distinct from, <i>C. revolute</i> (see Yamamoto, 1928; for an excellent comparison between them), whereas <i>C. taiwaniana</i> is definitely a member of another species-group that embraces at least <i>C. szechuanensis</i> and <i>C. hainanensis</i> in addition.

分布

• 台灣 : This species is endemic in Taiwan, but only two populations are so far known. Both are located in Taitung. In both localities the cycad individuals generally thrive in full sun on rocky and steep slopes or well-drained gravel land of ca. (300–) 400–800 (–

引證標本

TAITUNG: Peinantahsi, Sasaki 2558, 2559, 2560, 2561, 2562, 2563, 2564; Yenping: Seisui-Matsuyama, Yamamoto & Goto s. n. 1928; Seisui-Kaede, Yamamoto & Mori 58 ; Cycad Reserve, Tsou 420, Tsou 422, Tsou 569, Tsou 572, Tsou 825 (Holotype, HAST).

參考文獻

• SHEN, CHUNG-FU and TSOU, CHIH-HUA, Flora of Taiwan, second edition 1: 547. 2004.  (Fl. Taiwan 2nd edit.)