On the Resin Ducts in the Leaf of Picea 
brachytyla, Pritzel. 
BY 
MATTHEW YOUNG ORR, 
Assistant in Laboratory, Royal Botanic Garden, Edinburgh. 
With one figure in the text. 
Picea brachytyla, Pritzel*, one of the flat-leaved Spruces of 
Western China, has now been in cultivation for a number of 
years ; but, as all who have studied Conifers will admit, it is by 
no means an easy matter to identify specimens of this Picea, with 
any degree of certainty, by its vegetative characters alone. The 
difficulty of separating this species from Picea complanata is a 
case in point, and it is recorded that Franchet himself referred a 
specimen of the latter to his “‘A bies brachytyla.”’ 
This difficulty of accurately placing a non-fruiting specimen 
is not confined to Picea brachytyla alone, but, if the unusual 
anatomical feature which has come under the observation of the 
writer, and which forms the subject of this note, should prove to 
be constant in the species, this problem of identification, in the 
case of Picea brachytyla at least, ought to be the more easily 
solved. 
In the leaves of Piceas, belonging to the Omorica section, there 
are, as is well known, two laterally placed, marginal resin ducts, 
which extend from the base of the leaf throughout its whole 
length, terminating abruptly immediately behind the apex. 
These resin passages are in contact with, or may be partially 
enclosed by, the hypoderm of the under side of the leaf. 
The more minute details of their morphology need not be dis- 
cussed here, since the chief purpose of this paper is to call atten- 
tion to the diagnostic feature referred to above, which has 
apparently been overlooked in the past, since no reference to it 
can be found in the literature appertaining to this species. 
Some little time ago, while examining microscopic preparations 
of the leaves of Picea brachytyla, grown in the Royal Botanic 
Garden from seed collected in Western Hupeh by the Veitch 
Expedition in 1900, it was noticed that in transverse sections, cut 
from near the base of the leaf, there were four resin ducts visible, 
* See Plantae Wilsonianae, vol. ii (x914), p. 33. 
_ R.B,G,, Edin., No, LXVII, April 1923.] 
