J. M. Macfarlane. — Sarraceniaceae. 



with embryological, morphological, evolutionary and taxonomic evidence, and is more 

 fully treated in the Annais of Botany [III. (1889) 2 53]. There, however, he accepted 

 the terms dorsal and ventral in a sense that now seems to him inappropriate, and 

 in the succeeding descriptions he has returned to the older usage of "ventral" for the 

 upper, and "dorsal" for the under leaf surface. 



A comparative study of the leaves of Heliamphora, Sarracenia, and Darlingtonia 

 shows that they are related to each other in advancing specialization in the order 

 named. In Heliamphora the seedling and adult leaves are fundamentally alike, and 

 consist of a petiolar midrib that bears at the base wide sheathing membranous wings 

 (Fig. 1 Ba). These become slightly contracted above the base of insertion as in many 

 species of Nepenthes, but again reexpand to form petiolar wings (b) in front of the 



midrib. The latter becomes inflated 

 and excavated, from near the leaf 

 apex downward, to form the pitcher (d). 

 In front of this the wings that again 

 have contracted, reexpand into the 

 halves of the lamina, that appear as 

 longitudinal foliar excrescences diverg- 

 ing from each other, and from the 

 pitchered midrib that bears them (e). 

 The homological relation here with 

 many species of Nepenihes is perfect. 

 In small young leaves of Heliamphora 

 the margin of the orifice of the pit- 

 chered midrib, is rather sharply re- 

 flexed on either side to form a narrow 

 collar, but in adult leaves the top of 

 the pitcher gradually widens out into 

 a straight margin. In seedling and 

 in small adult leaves, the posterior 

 midrib apex is slightly prolonged above 

 the mouth into an acuminate process, 

 but in larger leaves this bears lateral 

 laminar expansions that together form 

 a circular or ovate lid (Fig. 2 Ä). 

 This lid is constricted off from the 

 pitcher orifice, and may measure 

 10 — 15 mm across. 



Each annual growth of leaves 

 of Sarracenia : in contrast to those 

 of the two other genera, is always 

 dimorphic, and frequently trimorphic, 



ab a 



Fig. 1 . Relation of leaves in Sarraceniaceae to simpler 

 leaf type. A Diagram of simple leaf type. — B Dia- 

 grammatic leaf of Heliamphora. — G Diagram, leaf of 

 Sarracenia. a sheathing base of petiole, b winged 

 {A, B) or cylindrical (C) part of petiole, c expanded 

 (A, B) or fused (0) halves of lower laminar portion, 

 d uniform (A) or inflated and pitchered B, G midrib 

 of lamina, e supposed (A) or actual (B, G) invagina- 

 tion orifice in pitcher formation , f terminal lobes of 

 lamina (J.), that form lateral parts of lid in B, G. 

 (Original.) 



but easy gradations from one type 

 to another can often be noted. The three types are: (a) petiolar scale leaves, that 

 function as winter scales, and are present in all the species, though in variable number; 

 (b) pitchered leaves that act as animal-chiefly fly-traps, and which apart from the scales 

 are alone developed in S. rubra and S. minor, are chiefly formed in S. psittacina, S. 

 purpurea and 8. Sledgei, and are about equally or rather more abundantly produced 

 in S. flava (Fig. 1 b, e) and S. Drummondii than are those of category (c). Those 

 of type (c), which might be termed "laminar phyllodia", clearly represent reduced 

 pitchered leaves that have developed a petiolar and inferior laminar portion, but have 

 failed to produce the superior pitchered part of the lamina (Fig. 1 c). That the second 

 or pitchered leaf is the primitive type for the genus, from which the first and last 

 have been derived, is shown by these always and only being formed on the seedling 



