— 
KEY TO SUB-CLASSES, ORDERS AND GENERA. 187 
CXIII—CYCADACEA—cont. 
with starch, Mucilage canals, often branched and anastomosing, lined by thin-walled 
secreting cells, are frequent in the bark, whence they extend to the leaves, and they are 
also found in the pith. Wood, cambium, bast, and medullary rays, are arranged as in 
Conifers ; the*wood, apart from medullary rays, consists entirely of long tracheides, more 
or less radially arranged, usually with several lines of bordered pits on the radial face, 
the pits oblong, not circular as in Conifers. ‘hese tracheides in some cases have spirally 
and scalariform thickened walls, and they might, save that their ends are not perforated, 
be classed as vessels. The fibro-vascular bundles (leaf traces), which enter the petiole, 
run for a considerable distance through the bark before joining the central cylinder ; 
their course is not straight, they are bent in aremarkable manner, and often anastomose. 
In Cycas the action of the cambium ceases after the first central cylinder (wood and bast) 
has been formed, and then a fresh, more or less concentric, cambium layer appears in the 
bark, which forms a second ring of wood and bast outside the first, and this process 
is repeated several times, the result being, on a transverse section, a number of more or 
less concentric masses of wood, which sometimes anastomose, separated by softer 
layers of bast and parenchymatous tissue. | 
[Botanical note.-~-Originally the plants of this order were supposed to be ferns ; 
then by others, inter alios Linnzus, intermediate between ferns and palms, whence 
they are commonly called Fern-palms; then Lindley pointed out that they are really 
almost firs with a palm-like appearance ; and their more correct name is Palm-jirs, | 
(1) Leaves simply pinnate, pinnee linear ;— 
(i) Pinnz with prominent midrib ; scales of female cones elongated, 
woolly, with two or more erect ovules on each side of the marginal notches :— 
cmxiv——Cycas, 
(ii) Pinnz ecostate, but with several longitudinal, scarcely prominent, 
nerves ; scales of female cones with 1 pendulous ovule on each side under the 
thickened acuminate apex :— wen er ae is emxyv — Macrozamia. 
(II) Leaves bipinnate, pinnules obliquely ovate or broadly falcate with 
scarcely prominent veins ; cones of Macrozamia, but apex of the scales trun- 
cate :— cee Ase tae APA ae *... ¢mxvi—Bowenia, 
CXIV—-ORCHIDACE A-- 
(1) Epiphytes or climbers ; ovary and fruit 1-celled, seeds minute ; sepals and 
petals very unlike the modified lip; anther single :— 
(i) Pollinia waxy :— 
(1) Pollinia free, or those of each cell held together by a viscid appendage 
only, and not attached by their bases, nor by a cardicle to the rostellum :— 
(A) Pollinia 4:— 
(a) Leaves sessile fleshy, congested on short, or distichous on elong- 
ated, stems with the vaginal portion much shorter than the main 
leaf ; inflorescence terminal; flowers minute, racemose or spicate; 
column very short with no appendage or foot:— cmxvii—Oberonia. 
(b) Leaves membranous, chartaceous or coriaceous, not equitant : — 
(¢) Leaves usually 2, membranous (rarely more, or coriaceous), 
usually sessile ; stem pseudobulbous ; inflorescence terminal in 
spikes or racemes, column long, produced below as a foot, 
with callosities or wings, or both, rostellum sometimes double ; 
lip without basal auricles :— +.  emxyviii—Liparis, 
(8) Leaves chartaceous or coriaceous :—— 
(*) Column more or less prolonged below as a foot :— 
(t) Stems solitary or, more usually, czespitose, or composed of 
discrate pseudobulbs basally attached on a short or long 
rhizome :— 
(§) Flowers terminal from the top of a 1-—2-leaved psendo- 
bulb, or lateral on a leafy or leafless stem, solitary or 
on few flowered peduncles, or in few--or many—-flower- 
ed racemes, usually large and showy :— 
(||) Stems czspitose with leaves chartaceous or coriaceous 
and more than 2, rarely a creeping rhizome with 
distant pseudobulbs and 1—2-apical leaves; pollinia 
all subequal aud always free ; lip rarely mobile :— 
cemxix—~Dendrobium. 
(|||) Rhizome creeping ; pseudobulba 2-(rarely 1-) leaved ; 
leaves coriaceous, or chartaceous and pleated; pollinia 
