Chapter III — 43 — Darlingtonia 



as a lure. Light green at first, the color gradually deepens and at 

 last becomes splashed with red. The roof of the dome and the back 

 of the upper part of the tube are mottled with numerous white flecks, 

 devoid of chlorophyll, glands and hairs, and, to an insect at the 

 mouth, form a visual lure {4 — 4, 5). Such fenestrations or areolae 

 are found in Sarracenia minor, S. psittacina, and S. Drummondii and 

 perhaps some others. The transparency of an areole is traceable to 

 the entire absence of chlorophyll-bearing tissues and of intercellular 

 spaces. Each areole lies in a mesh of the vascular tissue surrounded 

 by an irregular edging of chlorophyllous tissue with, inside, stomata, 

 glands and blunt curved downward pointing hairs, the latter encroach- 

 ing a little more on the clear tissue, which is composed of wavy walled 

 epidermis on both surfaces, with three or four courses of thick-walled, 

 perfectly clear cells. There is no pigment of any kind, except in old 

 leaves, when a yellow tinge may be detected. So complete is the ab- 

 sence of air-spaces and pigment, that the areole is quite glassy. A 

 few coarse starch grains occur especially toward the margins. 



We will now consider the structures about the mouth. We note 

 in the first place that the ventral wing just below the mouth as in 

 all the Sarraceniae has a doubled edge, less conspicuous in some species 

 (S. purpurea) than in others (S. minor). This is most conspicuous in 

 Darlingtonia, in which the double margin may be traced down a long 

 way and appears, as it did to Torre y and to Kurtz, to be continuous 

 with the edges of the basal stipular wings. The embryology shows, 

 however, that this is not the case {See beyond). If it were not so, 

 then we should have to explain a condition in Darlingtonia which is 

 not common to the Sarraceniae. As the evidence indicates, the ven- 

 tral wing or keel originates in the same way in both these genera. 

 The condition in Heliamphora, which has a pair of independent wings, 

 cannot in the absence of embryological evidence be brought into 

 comparison, as Troll also remarked. 



Now these two admittedly shallow free edges of the keel mark 

 the margins of the mouth. In Darlingtonia they may be traced along 

 the nectar roll and marking its outer limb. The wing edges are ac- 

 companied by the major wing veins, and these run forward to the 

 base of the fishtail, and enter it, one on each side, where they branch. 

 The appendage receives the end of the midvein also, but this 

 immediately branches. The fishtail is evidently due to deep emargi- 

 nation, as Goebel maintained, and is not a pair of pinnae, as Mac- 

 FARLANE believed. The condition in Darlingtonia is not parallel to 

 that in S. psittacina, in which the inrolled edges of the flap lobes 

 form valves with a weal along the edge of each representing the nectar 

 roll, but not of the same form. This receives only a minor branch of 

 the keel veins, which continues along the margins of the flap lobes. 

 In Darlingtonia the nectar roll results from hypertrophy of the leaf 

 edge in a lateral direction. The strong venation is correlated with 

 the supply necessary to the fishtail with its large number of active 

 glands and its large size. As already remarked, the veins running 

 along the outer Hmb of the nectar roll (5 — 7-10) pass forward to 

 enter the fishtail near its outer margins, there branch and furnish 

 the main supply lines. One readily infers that the outer marginal 



