1914] LLOYD—PINUS RADIATA 319 
The character of the shoot produced by proliferation of the 
fascicular bud is worth further notice. As seen by the text figures, 
the leaves succeeding immediately on the fascicled leaves may be 
either true scale leaves (fig. 2, A and B), or the same hypertrophied 
(fig. 1, B), and hence of juvenile character; or again, new fascicles 
may be produced at once in the axils of the three leaves of the parent 
fascicle (fig. 1, A), thus showing that fascicled leaves may subtend 
axillary buds. Far more rare than any of the preceding is the 
elongation of the axis of the spur shoot below the fascicled leaves 
instead of that above, as I found to occur in P. Taeda after injury. 
In such cases the leaves of the fasciculate whorl (fig. 2, A) do not 
attain their normal shape and dimensions, but are wider at the 
base and taper somewhat toward the apex, thus approaching 
hypertrophied scale leaves in form. Here, therefore, we have 
arrested fasciculate leaves and over-developed scale leaves approach- 
ing a common type, which probably simulates the form of the 
scattered leaves of the progenitors of the pines. 
From the point of view of comparative morphology, it seems 
logical and in accordance with the facts to argue with THOMSON 
that the type of fasciculation seen in Pinus is a highly specialized 
condition, derived from a prototype in which the spur shoots are 
not limited in growth. As THomson, however, has taken up this 
question in the paper referred to, I leave it here. The degree of 
physiological plasticity displayed by various species of the genus, 
and especially the amount shown by particular ones, notably 
Pinus radiata, argues, in my own mind, for a comparatively recent 
origin of the kind of spur shoot characterizing it. The evidence 
above cited appears to favor the view that abundance of water is 
of prime importance in disturbing the ordinary equilibrium, and 
thus stimulating the proliferation of spur shoots. 
McGrz Unrversiry 
EXPLANATION OF PLATE XIV 
A, small tree of Pinus radiata from which are absent the normal whorls 
of branches; the dense fox-tail effect is due to very numerous proliferated 
Spur shoots; B, piece of a branch of another tree of the same species, showing 
the numerous proliferating spur shoots. 
