186 TRAXSACTIOXS AND PROCEEDINGS OF THE [Sess. lv. 



Hilgarcl * state that " the resin of this shrub collected by 

 the Pinios Indians is formed by them into balls which they 

 kick before them with their feet as they journey from one 

 point to the other of their trail." The dried specimens 

 retain the excretion in quantity, and, if not poisoned, they 

 will preserve the odour for many years. 



The wood is extremely hard and tough, showing great in- 

 duration of the xylem-elements. Prismatic and clustered 

 crystals occur in great numbers, especially in the bast, where 

 they are generally densely packed.t Clustered crystals are 

 present in the leaves and stipules of all the species, and 

 they have been found in the sepals, petals, and pistil of 

 L. mexicana and L. cuneifolia. 



The leaves of L. mexicana'^ are composed of one pair 

 of small crescentic pinnse on a short petiole. A minute 

 apical prominence lies between the pinna?. They are 

 covered on both surfaces with fine hairs which are 

 unicellular, elongate, tapering gradually to a sharp point, 

 and all directed to the apex of the leaf by a bend near 

 their base. . Their roots are placed in a depression of 

 the epidermis. The young branches are also covered with 

 similar hairs. Stomata occur in great numbers on both 

 sides of the leaf. They are slightly elevated on papillae. 

 Under the action of caustic potash the one or two circles of 

 cells immediately surrounding the stomata are rendered 

 clearer, and the rest appear entirely filled witlf a brown 

 substance. The hairs remain colourless. Considering the 

 manner in which the excretion is found over the whole leaf 

 surface, and seeing that it is unlikely to be derived either 

 from tbe hairs or the cells bounding the stomata, it may be 

 concluded that tlie intervening cells are excretory. 



The stipules are objects of very considerable interest. 

 Two pairs occur at eacli node. At first the pairs are closely 

 approximated. They are small, obliquely cordate, and 

 resemble the leaves in colour and in being clothed, although 

 more sparsely, with similar hairs. Very soon, indeed at the 

 second fully developed node, they assume a reddish colour 



* Botanical Report of Explorations for a Railroad Route, Washington, 

 1855. 

 t FwZc Sachs, ]'hysiolo;,'y of Plants, p. 177. {G'uaicum officinale.) 

 t iMoricand, I'l. nouv. Amor., t. 48, p. 73; A. Gray, Gen. 111., t. 147. 



