Chapter II — 31 — Sarracenia 



back mass (abaxial side) of the leaf base (Goebel i88i), which 

 then enlarges its own apex behind and above the "primary leaf apex," 

 that of the leaf base proper. 



The development of the embryo leaf follows the same course except 

 that the upper side of the primordium of the lamina is not completely 

 suppressed but is limited to a minute depression between the leaf 

 base and the apex of the leaf blade (Oberblatt). This is limited 

 below by an as yet extremely narrow transverse zone, which cor- 

 responds to the transverse zone of a peltate leaf, and at the same 

 time may be taken as an indication of a unifacial petiole primordium, 

 one, however, which experiences no further development. It is im- 

 portant to note that the leaf blade apex does not rise much above 

 that of the leaf base and that therefore the leaf blade stands nearly 

 normal to the base. This, however, soon changes. The apex now 

 grows rapidly and the primordium widens, flattening dorsiventrally, 

 and changes in curvatures ensue to produce the helmet-shaped form 

 of the lid. Meanwhile the adaxial side elongates and the keel appears, 

 below which the transverse weal of the leaf-base runs; otherwise said, 

 the edges of the leaf base are not concurrent with the keel. The 

 similarity to the Iris leaf is unmistakable, only allowing that the leaf 

 blade is hollow. Thus the unifacial character of the leaf blade comes 

 into expression, not as a shallow saucer but as a narrow furrow. The 

 upper side of the lamina primordium is at first confined to the adaxial 

 side of the leaf blade. Growth progresses less by spreading than by 

 upward growth of the margins to form the tubular leaf. The petiole 

 is not developed, but instead the blade greatly lengthens, in S. flava 

 to the extent of i meter. The terminal portion, whose edges are 

 free, becomes the lid. 



I have examined the development of the leaf of 5. minor and can 

 generally agree with Troll. In this species, however, the primordia 

 stand out perhaps more clearly because of the greater tendency to 

 grow in length, as compared with S. purpurea. In this, however, all 

 leaves do not act ahke, for there is sometimes a greater lengthening 

 of the petiolar region, so that even in this species the petiole is not 

 absent, though normally much reduced (2 — 12). 



In S. minor the earliest stage of development available was a leaf 

 only 0.1 mm. in height in the form of a low cone, its base reniform, 

 about 0.4 mm. in greatest diameter, its convex edge adaxial (3 — 13). 

 The extremities of this edge had a talus-like slope, the cone melting 

 into the overhanging front of the body of the leaf. This rose to a 

 very low apex, evidently a growing point, scarcely evident as a 

 distinct boss. There could be seen a very shallow groove from the 

 top down the adaxial face of the overhanging mass. In this very 

 early and undifferentiated condition there is recognizable a leaf base 

 with very thick edges, a groove, a sign of the coming invagination, 

 and a very low boss. It is not, however, possible to locahze a definite 

 growing point for the leaf base, while even at this young stage, the 

 apex of growth of the leaf blade is just visible. 



In a leaf 0.3 mm. (j — 14, 15) in height the apex stands out well, 

 and below it adaxially one now sees a short groove, the leaf base 

 margins distinctly passing transversely across, some distance below 



