Notes on the Life-History of Pterostylis. 
BY 
OSWALD H. SARGENT. 
With Plates XVIII and XIX. 
P TEROSTYLIS is a genus of small terrestrial herbaceous orchids. Its 
members are chiefly found in Australia (including Tasmania). About 
forty-five species are known. One of these extends to New Caledonia, and 
several extend to New Zealand, the home of several species not found else- 
where. So far, ten species, viz. P. reflex a, constricta , nana , pyramidalis , 
recurva , vittata , Sargenti , rufa> barbata , and turfosa , have been reported 
from Western Australia. One of these, barbata , has not been seen by 
collectors for many years. All the remaining nine I have found within 
a few miles of my home (at York, W.A.), and have carefully observed them 
for several years. I have also cultivated the majority in flower pots. Upon 
these observations and experiments the present paper is founded. As the 
genus is a very natural one, there is little doubt that my conclusions based 
upon the study of a part will hold good with but little modification for the 
whole. 
During the hot, dry summer months the plant exists as a small globular 
succulent tuber, buried two or three inches below the earth’s surface. This 
tuber is strangely lacking in protective covering. There is no layer of dead 
fibrous tissue, as in Caladenia or Glossodia , and even the cuticle is remark- 
ably thin. Doubtless the fibrous soil in which the plants grow forms a 
sufficient protection against undue loss of moisture. Some dormant tubers 
of P. Sargenti rapidly became flaccid when taken out of the ground ; while 
on the other hand a tuber of P. rnfa kept in a loosely covered box remained 
turgid right through the summer. 
On the advent of the winter rains, about May, the tuber puts forth 
a single shoot. This grows rapidly, and as it grows develops numerous 
short processes all over each internode (subterranean). These processes are 
truncated cones of tissue whose apical layers consist of a number of thin- 
walled grape-shaped cells. These cells are attached at their bases only, and 
their function is without doubt the absorption of food salts from the soil. 
[Annals of Botany, Vol. XXIII. No. XC. April, 1909.] 
