Chapter III — 41 — Darlingtonia 



scarcely exceed the stomata in size. These glands are found even 

 on the outer surface of the overhanging apex. The inner surface can 

 be roughly divided into three zones. The uppermost embraces the 

 whole of the apex and some distance into the interior from the open- 

 ing. The inside surface of this portion is furrowed longitudinally from 

 the extreme apex to a point well within the tube. The floor of this 

 furrow is lined with smooth epidermis which for some distance forms 

 a low swelling on each side of the furrow. Among these cells are a 

 very few groups which have distinctly the structure of a nectar gland, 

 but I have not been able to determine positively that nectar is se- 

 creted. They seem not to be quite so highly speciaHzed in form at 

 least as the glands of a mature or adult type of pitcher. The epider- 

 mis in general of this zone is of the "fishscale" type, that is the cells 

 are imbricated and are downwardly sharply pointed, the more sharply 

 the more deeply placed in the pitcher. As zone 2 is reached, fewer 

 of the cells are trichomes, which are now much longer, the remaining 

 cells being quadratic and elongated to some extent. In the depths 

 of the pitcher, hairiness ceases, and the epidermis, in zone 3, is quite 

 smooth. Like the senile leaves, the juvenile tube leaf is twisted 

 through 180 degrees from base to apex, so that the opening comes 

 to face downwards, more or less. In size they may be as small as i 

 cm. and up to 10 cm. 



Occasional juvenile leaves display aberrancies from the normal 

 course of development. Rather frequently one finds a leaf with the 

 apex forked, and having no median vein, clearly corresponding to 

 the fishtail appendage of the adult leaf. Accompanying this con- 

 dition there may or may not be developed an ala ventralis. In most 

 cases the rim of the mouth remains simple, but in one leaf I found 

 that a distinct nectar roll had been developed along both sides, but 

 not meeting anteriorly, as in the adult leaf, to fuse {5 — 3)- This 

 indicates pretty clearly that the place where the two sides of the 

 nectar roll meet is a site of concrescence in the fully elaborated leaf. 

 As in all these forms of juvenile leaves there are nectar glands, which 

 are confined to a broad band along the inside of the hood and apex 

 but not elsewhere on the inner surface ((5— 18). The epidermis is 

 all of tesselated umbonate cells above, becoming longer pointed further 

 down. The glands are not quite so elaborate here as in the adult 

 leaf. Those on the outer surface are typical in appearance. 



A single juvenile leaf was found in which there was a closure of 

 the mouth for only a short distance above the base. What might 

 have been the tube was laid quite open, and formed no trap at all. 

 Glands were present on the apical appendage and along a midband, 

 as usual. The epidermis was tesselated. That is, the leaf was a nor- 

 mal juvenile leaf in all respects except that the edges remained free 



(5-6). 



Cases of this kind might be used as evidence that the pitcher 

 arises by fusion of the leaf margins (Macfarlane) but can as well 

 be explained as resulting from disharmony of growth. On various 

 grounds another explanation is to be preferred. (See beyond). 



It may be noted in the juvenile leaves that the margins of the 

 "total stipule" (Troll) run far up the petiolar region. In a juvenile 



