47 



Although the characteristics of the rhizomes contribute in no 

 small degree to the success of this domineering plant, the leaves 

 are the main visible feature. The petiole closely resembles the 

 rhizome in size, color, and texture. It is slender, Yz~yi '^ich in 

 diameter, and of variable height depending upon ecologic con- 

 ditions. The height varies from a few inches to lo or 15 feet; 

 plants clambering up into trees and bushes often have petioles 

 much longer than this. The petiole is terete, not sulcate, 

 flexuose below, and notably erect and rigid. It is smooth, hard, 

 tough, and brittle. Its texture and surface is much like that of 

 bamboo; at the forks and buds it is wooly-tomentose. In cross- 

 section the petiole much resembles the rhizome. 



The young petiole looks like an erect piece of heavy green 

 wire, 10-30 inches high, and rolled at the apex into a tight spiral 

 about I inch in diameter. The petiole-base is brown and hard, 

 the upper portion and spiral are quite soft and green. All parts 

 are glabrous except the spiral, which is sparingly clad with ap- 

 pressed brown hairs. The spiral unrolls and bifurcates, re- 

 peatedly forking in the upper portion at open angles, the ultimate 

 pair of branches frondose. 



On the summit of the petiole is the leaf-blade or frondose por- 

 tion. This comprises a series of dichotomously branching rami- 

 fications. The lower are the largest and most mature, the upper 

 tiers or strata of pinnae are progressively younger. In the axil 

 of each bifurcation is a small bud, covered with brown wool; by 

 means of these buds the growth may continue more or less 

 indefinitely. Usually the bud in the first or lowest fork develops 

 into a strong rachis, also dichotomously branching, and giving 

 the leaf a loosely pinnate appearance. The leaf may thus have 

 three or more, tiers of pinnae, with a total of several hundred 

 pinnae. 



Each pinna or frondose branch is rigid, chartaceous, glaucous 

 underneath, glabrous, elliptico-oblong, 6-9 inches long and 2>^- 

 4 inches wide, broadest about the middle. The pinna is divided 

 down to the rachis into closely set, blunt pinnules; these are at 

 right angles to the strong midrib, and are linear, 1^-3 lines 

 broad, entire, obtuse or emarginate. The inner or upper pin- 



