168 BOTANICAL GAZETTE [AUGUST 
In soft-wooded species (fig. 2), on the other hand, well known as 
being prevailingly fat trees, the vertical and ray parenchyma is 
thinner-walled and less heavily lignified, and the cells of the rays 
tend consequently to be irregular in shape, with oblique or bulging 
end walls, an outline quite different from the prevailingly rigid and 
rectangular one of starch tree parenchyma. They are well provided 
with pits or are so thin as not to require pitting. 
Fic. 1.—Nyssa sylvatica, a starch tree: portion of medullary ray of wood seen in 
radial section as it crosses fibers (at left and right) and a vessel (in center); note 
thick-walled, squarish ray cells; small pits between ray cells and from ray cells to 
fibers; and large pits from ray cells to vessel. 
Of particular significance are the exceptions already noted to 
the general rule that there is a connection between hardness of wood 
and type of food reserve. The hard-wooded pines, for instance, 
are filled with fat, a circumstance evidently related to the fact that 
their ray parenchyma and resin canal epithelium (the only seats 
of storage in the wood) are unlignified and very thin-walled. In 
Liriodendron, Magnolia, Ailanthus, and Platanus, on the other hand, 
which are soft-wooded but which we have nevertheless observed to 
contain starch, the rays are made up of thick-walled rectangular 
