|Photo Ken Hill
|The Cycad Pages
- Cycas yorkiana K.D. Hill, "Telopea 7(1): 18-19, fig. 8" (1996). H—NSW
- "TYPE: Australia, Queensland, 20.5 km N of Wenlock River crossing on Bamaga road, K.D. Hill 4711 & L. Stanberg, 11 Jul 1994 (holo NSW; iso BRI, CANB, DNA, K, L, MEL, NY)."[NSW][NSW]
From the occurrence of this taxon in Cape York Peninsula.
|Photo Ken Hill
Hill 1996, fig. 8.
ALthough abundant along the only road through this region, this species
was poorly collected and confused with C. media until 1994.
Distinguished from other Australian species by the
bright green, keeled leaves with keeled and usually falcate leaflets,
the short, soft cataphylls, and the thick crown of orange wool
around the cataphylls. The closely allied C. badensis differs
in having a smaller megasporophyll apex with fewer and shorter
lateral spines and a shorter terminal spine, somewhat less orange
wool in the crown, and leaflets that are usually straight rather
than falcate. C. campestris from New Guinea has similar
keeled leaflets, but also rarely falcate, and with narrower bases.
The latter species is also distinguished by the broader megasporophyll
lamina with longer lateral teeth (see Hill 1994). The orange wool
around the cataphylls is not present in most other species in
this group, but occurs in a number of other more distantly related
species such as C. cairnsiana, C. ophiolitica, C.
maconochiei and C. lane-poolei.
Extremely abundant in northern Cape York
Peninsula in an apparently very localised within an area lying
to the north of the Wenlock River. A small disjunct population of
somewhat more robust plants occurs on
quartzite hills near Cape Melville. A single specimen apparently
from Rokeby (Gordon s.n.) belongs to this species, although
this would be from within the range of C. xipholepis. C.
yorkiana usually occurs as an understorey plant in open Eucalyptus
miniata -- E. tetrodonta forest on flat country, on sandy
soils over laterite, although the Cape Melville population is on stony
Abundant but localised, not considered
to be at risk.
|Photo Ken Hill
Stems arborescent, to 4 m tall.
Leaves bright green, semiglossy, 90-140 cm long, slightly keeled to flat (not keeled) in section (opposing leaflets inserted at 150-180° on rachis), with 160-220 leaflets, with orange tomentum shedding as leaf expands; rachis consistently terminated by a spine 5-20 mm long. Petiole 17-28 cm long (15-25% of total leaf), petiole glabrous or pubescent, spinescent for 5-90% of length. Basal leaflets not gradually reducing to spines, 30-50 mm long.
Median leaflets simple, strongly discolorous, 140-190 mm long, 5.5-7.5 mm wide, inserted at 60-75° to rachis, decurrent for 3-5 mm, narrowed to 4-5 mm at base (to 55-80% of maximum width), 9-11 mm apart on rachis; median leaflets section slightly keeled; margins slightly recurved; apex acute, spinescent; midrib flat above, raised below.
Cataphylls narrowly triangular, soft, densely floccose, 60-80 mm long, persistent.
Pollen cones not seen, orange or brown, 8.5 cm diam.; microsporophyll lamina firm, not dorsiventrally thickened, 35 mm long, 12 mm wide, apical spine 6 mm long.
Megasporophylls 21-32 cm long, grey-tomentose; ovules 2-6, glabrous; lamina lanceolate, 60-100 mm long, 17-32 mm wide, regularly dentate, with 24-32 pungent lateral spines 3-6 mm long, 1-2 mm wide, apical spine distinct from lateral spines, 12-16 mm long.
Seeds flattened-ovoid, 34 mm long, 30 mm wide; sarcotesta orange-brown, not pruinose, 4 mm thick; fibrous layer absent; sclerotesta smooth. Spongy endocarp absent.