10 J. M. Macfarlane. — Sarraceniaceae. 



in the lignified hypodermal cells. The endodermis is an evident layer of bead-like 

 cells, with the usual radial wall thickening. Within it is a single pericambial layer, 

 from which originate the numerous short lateral rootlets, each in line with a protoxylem 

 tract. The bündle System consists, in its proto-elements, of 5 to 6 deep wedge-shaped 

 patches of protophloem, between as many protoxylem arms. The protophloem shows 

 a mass of small centrally placed cells, surrounded by large sieve tubes. The protoxylem 

 is made up of a few spiral tracheae at the ends of the arms, of highly lignified fibre- 

 cells in Clusters or as isolated elements, and of starch-storing companion cells, that 

 Surround and unite the fibres. 



Secondary growth proceeds by formation of cambium on the inner faces of the 

 protophloem patches, and the development by it of metaxylem and metaphloem. The 

 metaxylem consists of tracheids, of food-storing cells, and of large vessels with pitted 

 lateral walls and oblique scalariform septa. No metaphloem is formed as a rule on 

 the outer side of the root cambium, which is therefore operative only on its inner side, 

 but occasionally two layers of tissue are produced on the inner side of the pericambium 

 that serve to unite the protophloem patches. The short lateral rootlets all arise in the 

 pericambium, and as many as three may be sectioned in one plane. 



The roots of Darlingtonia agree closely in description with that given above, 

 except that the three hypodermal layers are little if at all thickened, while the inner 

 cortex is denser and more continuous. The number of radial vascular patches, also 

 the mode of origin and the Constitution of these, agree in both . 



Stern. In Sarracenia the epidermal layer of mature rhizomes is of a brown 

 color as in mature roots. This is again due to a pigment in the cell cavities, which 

 early Alters into and pigments the walls. Subjacent to the epidermis are two to three 

 layers of indurated hypodermal cells, the outermost of which are most strongly 

 lignified. These contain considerable quantities of starch. Subjacent is a wide zone 

 of food-storing cortex cells, that are continuous in appearance and food-storing capacity 

 with cells of the medullary rays and of the pith. Embedded in this extensive mass 

 of storing cells is a discontinuous ring of vascular bundles of varying size and shape, 

 and that are separated from each other laterally by medullary rays of very unequal 

 width. Each fully formed bündle shows, next the pith, a few (2 — 5) spiral tracheae, 

 surrounded by companion protoxylem cells. Outside these are one or two small isolated 

 patches of pitted tracheids, surrounded by companion cells. The bündle then assumes 

 a highly lignified character, and consists of metaxylem, in which a heavy patch of 

 wood tracheids or fibres occupies the front part. This is succeeded by a mass of 

 intermixed pitted vessels and wood fibres. Beyond the intrafascicular cambium of 

 each bündle is a patch of normal bast or phloem. Slow and limited increase o^ each 

 bündle goes on for 5 to 8 years, but no recognisable difference can be traced in the 

 annual growths, that would demarcate them into rings. 



In Darlingtonia the epidermal layer is likewise brown. Two to three hypodermal 

 layers with slightly thickened walls, are succeeded by a broad rather dense cortex, that 

 stores only a moderate amount of starch. The walls of the cells of this zone are 

 somewhat thickened, and are traversed by canals with pore plates in their middle. The 

 endodermis is a sinuous layer, of rather large cells, that bounds the pericambium. 

 This consists of one, or by early division of 2 — 3 layers of thick walled cells, that 

 simulate a fibrous phloem zone. Unlike Sarracenia the present genus forms a continuous 

 cylinder of vascular bundles, from which leaf-trace bundles and root bundles are given 

 off. The only slight point of difference here, as compared with Sarracenia, is that 

 the tracheids and pitted vessels are more uniformly intermixed. But the structure of 

 the leaf-trace bundles is exceptional. As each trace separates from the stem ring, the 

 phloem closes in round the xylem, and from near the point of Separation up to the 

 insertion of the leaf, the bündle is a typical concentric one. It consists of a central 

 xylem surrounded by a zone of phloem, that is made up of patches of phloem cells 

 united by sieve tubes. The whole is enclosed by an indurated pericambium and 



