J. M. Macfarlane. — Sarraceniaceae. \ \ 



accessory cortex tissue. Slightly above the base of the petiole the 3 — 5 concentric 

 bundles that have entered it, break up into parts that Orient themselves bifacially, and 

 then run lengthwise into the pitcher-walls. 



Leaves. Since the pitchered leaves of the Sarraceniaceae are highly specialized 

 in histological detail for an exact physiological purpose, they can best be studied from 

 the histological standpoint when the physiological use is kept clearly in view. Since 

 the epidermal surfaces are the important areas connected with the catching of animal 

 prey, these deserve special consideration. Following the nomenclature of Hooker f. and 

 of the writer, it may shortly be said that the external epidermis of each leaf is well 

 supplied with honey glands, and in a few species with up-directed hairs that tempt 

 small animals, chiefly insects, toward the pitcher mouth. The entire outer epidermis 

 may therefore be named the "alluring" surface. The inner face of the lid in Heliam- 

 phora and Sarracenia (Fig. §Ba), and the inner face of the bilobed Aap, as well as 

 that of the cucullate hood in Darlingtonia, are richly studded with honey-secreting 

 glands, interspersed with down-directed hairs. This region can appropriately be de- 

 signated the "attractive" surface. Succeeding to this is an extremely smooth area that 

 affords very insecure foothold for insects (Fig. 5 Bb), and from which they readily drop 

 deeper into the cavity. This has been named by Hook er the "conducting" surface. 

 Beneath is a deep zone that often Covers nearly the entire lower half of the cavity, 

 and that bears long tapered downwardly directed hairs. This is the "detentive" sur- 

 face (d). The lowest part of the tube may at times be quite smooth, and may, ' like 

 a considerable portion of the detentive surface, show a shallow thin-walled epidermis. 

 Though scarcely deserving separate designation it may be termed, for convenience, the 

 "absorptive" surface. 



In Heliamphora each leaf shows many nectar glands over its external surface, 

 from the base upward to the orifice. Along the laminar wings these glands are about 

 twice as abundant. Each gland consists of a patch of 6 — 8 cells over the lower part 

 of the pitcher, but of 9 — 12 in those near the orifice. Distributed amongst them are 

 bifurcated upwardly- directed hairs of rather delicate texture. The entire region« forms 

 the alluring surface. The inner surface of the relatively small lid is covered witn 

 nectar glands of comparatively large size, and of complex structure as seen in surface 

 view (Fig. 5 Da, b) and in section. These may be intermixed with others of smaller size, 

 and this latter type persists amongst downwardly directed hairs over y 3 to 1 / 2 of the 

 pitcher depth. Both areas evidently represent the combined attractive and conducting 

 surfaces. A smooth surface next succeeds. Its cells have wavy walls, and though 

 devoid of glands the zone seems to be comparable to the glandulär surface of Sarra- 

 cenia purpurea, that will afterwards be described. The lower part of the tube is 

 covered by wavy epidermal cells, from a few of which short heavily thickened hairs 

 originate (e). This is the detentive surface. 



The epidermal areas in Sarracenia vary somewhat according to the species, but 

 broadly agree in general details. In every species the external epidermis develops 

 numerous alluring glands, but upwardly directed hairs are absent, except in S. minor 

 and S. Drummondii, where they may be irregularly directed, or may point upward 

 in advantageous manner. In S. flava, S. minor and S. rubra the alluring glands 

 are much more abundant over the laminar wing than over the general pitcher surface, 

 so that this forms a special baited pathway upwards. The condition seen in S. flava 

 is specially noteworthy, for here in addition to glands over the general surface and 

 along the laminar wings, many are disposed along the strong prominent longitudinal 

 veins of the pitcher. During May and June these exude large glistening nectar-drops 

 that are highly relished by insects. In this species also, and to a less degree in the 

 others, the external rim of the lid is richly covered with nectar-glands, that act as an 

 allurement near the attractive lid surface. Stomata are abundant over the entire exterior 

 of the pitcher and over the wing, down even to the amplexicaul base, where however 

 they become scant. They are wholly absent over the upper surface of the amplexicaul 



