|Photo P.K. Loc
|The Cycad Pages
- Cycas dolichophylla "K.D. Hill, T.H. Nguyen & K.L. Phan", "Bot. Rev. 70(2): 157-160, fig. 7" (2004). H—HN
- "TYPE: Vietnam: Tuyen Quang: Na Hang, Pu La mountain, 2 Nov 1996, T.H. Nguyen 2124 (holo HN)."
From the Greek dolichos, long, and phyllon, leaf, referring to
the long leaves.
Although the most widespread and abundant cycad in northern Vietnam,
C. dolichophylla was recognized as a distinct species only in the
This species has been confused with C. balnasae in the past.
The robust though usually short aerial trunk, the larger and more numerous
leaves with red-brown tomentum and more numerous leaflets that are short,
broad and distinctively
rounded at the base, and the larger male cones readily distinguish
C. dolichophylla fromC. balansae
Megasporophylls are similar to those of C. balansae.
C. dolichophylla is also part of the complex of closely related
taxa that is distributed through northern Vietnam, Laos, northern Thailand
and Yunnan and Guangxi in southern China (Section Stangerioides).
Distribution and habitat:
Locally frequent in more sheltered sites in deep shade in tall closed
evergreen forests. A predominantly Vietnamese species, extending
from near the Chinese border in the north to Ben En NP
in the south, and west to a very short way into eastern Yunnan province
This species occurs on loamy soils over limestone, shale, schist or granite,
in closed evergreen forests, although today these are often reduced to
A population occurring west of the city of Moc Chau has narrow leaflets
with slender bases, short to medium petioles and small seeds, and is
interpreted as a zone of intergradation with C. collina, which is
abundant in higher country to the west. Plants observed in cultivation
around Vo Nhai and Yen Son districts, Thai Nguyen Province, were intermediate
in form between C. dolichophylla and C. ferruginea, and have been
interpreted as hybrid individuals. In this region, C. ferruginea
is abundant on steep exposed limestone faces, and C. dolichophylla
is abundant in adjacent closed forests on deep heavy soils.
Plants observed in cultivation in villages west of Thai Nguyen and
said to have been collected locally were morphologically intermediate
between C. dolichophylla and C. multifrondis.
There is no immediate threat of extinction, although the severe depletion
of populations over past decades indicates that conservation action is
appropriate, and this species is regarded as vulnerable,
IUCN Red List category VU A2c.
|Photo P.K. Loc
|Photo P.K. Loc
Stems arborescent, to 1.5 m tall, 18-30 cm diam. at narrowest point; 8-40 leaves in crown.
Leaves bright green to deep green, highly glossy, 200-450 cm long, flat (not keeled) in section (opposing leaflets inserted at 180° on rachis), with 150-270 leaflets, with orange tomentum shedding as leaf expands; rachis consistently terminated by paired leaflets. Petiole 40-110 cm long (20-35% of total leaf), petiole glabrous, spinescent for 90-100% of length. Basal leaflets not gradually reducing to spines, 90-240 mm long.
Median leaflets simple, strongly discolorous, 190-420 mm long, 14-25 mm wide, inserted at 60-85° to rachis, decurrent for 5-8 mm, narrowed to 3-6 mm at base (distinctively rounded at base) (to 20-35% of maximum width), 16-30 mm apart on rachis; median leaflets section flat; margins undulate; apex softly acuminate, not spinescent; midrib raised above, flat below.
Cataphylls narrowly triangular, soft, pilose, 80-120 mm long, articulated.
Pollen cones narrowly ovoid or fusiform, yellow, 35-50 cm long, 8-10 cm diam.; microsporophyll lamina soft, not dorsiventrally thickened, 30-36 mm long, 9-13 mm wide, fertile zone 27-34 mm long, sterile apex 2-4 mm long, level, apical spine rudimentary or absent, sharply upturned, 0-3 mm long.
Megasporophylls 15-26 cm long, brown-tomentose; ovules 2-4, glabrous; lamina orbicular, 60-120 mm long, 50-100 mm wide, deeply pectinate, with 16-26 soft lateral spines 40-50 mm long, 2-3 mm wide, apical spine not distinct from lateral spines.
Seeds ovoid or flattened-ovoid or oblong, 40-64 mm long, 33-36 mm wide; sarcotesta yellow, not pruinose, 2-4 mm thick; fibrous layer absent; sclerotesta verrucose. Spongy endocarp absent.