KUNGL. SV. VET. AKADEMIENS HANDLINGAR. BAND 55. NIO 5. 263 



strands in the cortex. The explanation of this fact is that the strands of the li- 

 gules are only mechanical in their character and not vascular bundles. The stone- 

 cells of the fruit as in the preceding group. 



In conformity with this segregation of the American forms, it might also be 

 necessary to conceive the Australian v. Muelleri A. Benn. as a separate species. 



P. Richardsonii (Ar. Benn.) Rydb. 



Studies on the Rocky Mount. Fl. in Torrey Bot. Club, 1905, 599. P. per- 

 joliatus L. v. lanceolatus Robb. in Asa Gray. Man. Bot., 1867, 488. — P. perfol. 

 v. Richardsonii Ar. Benn. in Journ. of Bot., 1889, 25. — Cf. Fernald, in Rob. and 

 Fern., Gray's New Man., 1908, 74! 



This species differs from P. perfoliatus by the following properties: 



1) Leaves more recurved, their nerves very densely placed, by which the leaves 

 of ten (at least the larger ones) become 19-nerved (15 — 25). The chief lateral nerves 

 join the midrib often in the very apex as is the case in P. perfol. and prcelongus, 

 but sometimes also a little beneath. Denticulation is another: In P. perfol. the 

 denticles are more prominent and directed outward, in P. Richardsonii the denti- 

 culation is very low and the tooth-cell has a broad base by which the cells almost 

 seem to be lying in a row along the margin, which makes denticulation very 

 characteristic and singular. 



2) The ligules differ as to length, form, and structure. They are more elongate, 

 more narrowed, though obtuse, and endowed with strong bast-strands connected 

 conspicuously with each other in the apex of the ligule. The interjacent parts are 

 membranous and easily dissolved, so that the fibers only soon are left. 



3) The stigma is lower and more like that of P. prcelongus. 



4) The fruit is said to be somewhat larger (Morong, Nai., 1893, 34). The 

 fruits I liave seen had the size of full-grown perfoliatus-ivuits, or the length of 

 about 3,25 mm. The beak may perhaps be somewhat more facial than is the con- 

 dition in perfol., i. e. more like that of prcelongus. The epicarp has the same rounded 

 form as in P. perfol., but the lid of the endocarp is built in conformity with that 

 organ in P. prcelongus. The fruit occupies in fact a perfect intermediate position 

 betvveen these two species: endocarp = prcel„ epicarp = perfol. 



As to growth and ramification the species resembles the two said species, 

 which in this respect are much the same. The form of the base and apex of leaves, 

 the peduncle and spikes seem to coincide with P. perfoliatus and the same is true 

 as regards the anatomy of the stem. The epidermis-cells are of the elongate type. 

 Someone or other subepidermal strand is sometimes observed, but so is the case, 

 though rarely, in P. perfoliatus also. The fact that the strong bundles of the ligule 

 do not descend into the bark as a ligular circle of bundles is noticeable. The reason 

 of this is that they lack ducts and are mechanical only in character. The ligular 

 circle always consists of vascular bundles. The anatomy of the peduncle is the 

 same as in P. perfol. 



