398 Hill . — The Morphology and Seedling Structure of the 
not only from Peru and Bolivia, but also from Guatemala and from Mexico. 
An examination of the original description and figures of the P. umbilicata 
of Ruiz and Pavon 1 shows that their specimen bore roots from the sides of 
the tuber ; but in the figure of P. umbilicata given in Humboldt and 
Bonpland 2 the tuber is globose, and the roots all spring from its upper 
surface, almost at the same spot, which is to one side of the point of 
insertion of the leaves. 
From these figures it is clear that P. umbilicata , R. and P., and 
P. umbilicata , H. B. and K., are distinct species, and the present confusion 
of the two is due to the fact that these differences in the tuber have not 
been recognized by Miquel, De Candolle, and others, owing perhaps to the 
general external similarity of these two species. There are several speci- 
mens from Mexico in the Herbarium at Kew which agree with P. umbilicata , 
H. B. and K., and P. gracillima , Wats., is undoubtedly a very close ally of 
these forms 3 . 
In addition to these, there is yet another species, collected by 
Pringle 4 in Mexico, and formerly considered to be a glabrous form of 
P. Miilleri , C. DC. As in the other cases mentioned, seedlings have been 
found which show the same monocotyledonous habit, but the mature plant 
possesses a well-defined creeping and somewhat tuberous rhizome. This 
plant, which has been named P. macrandra , C. DC. 5 , seems from the 
structure of its fruits and the character of its rhizome to be nearly related 
to P. mexicana , and is a totally distinct plant from the true P. Miilleri 6 . 
Fruit and Seed Structure. 
Dahlstedt in his monograph has laid particular stress on the fruits as 
affording reliable specific characters, and, as far as the geophilous species are 
concerned, I have found that they furnish very valuable evidence, especially 
when seen in longitudinal section, as to the probable relationship of the 
different species (Figs. 3, 8, 29, PI. XXIX ; Figs. 31 and 41, Pi. XXX). 
Moreover, owing to the retention of the fruit by the germinated seed- 
ling, there is no difficulty in the identification of seedlings which may be 
collected in the field. The details of the fruit-structure will be given when 
the several species are described, but with regard to the seeds it will be 
useful to make a few general remarks in this place. Owing to the similarity 
of the seeds of the species under consideration with those of P. pellucida , 
1 Ruiz and Pavon, FI. Peru, i, p. 30, Tab. 45, Fig. b. 
2 H. B. and K., Nov. Gen. et Spec., i, p. 59, Tab. xv, Fig. 1. 
3 The specimen from Guatemala included under P. timbilicata , R. and P., No. 1430, 
J. D. Smith (vide Dahlst., 1 . c., p. 31), is a new and distinct species. 
4 Pringle, No. 4654 in Herb. Kew and Herb. Brit. Mus., determined as P. Miilleri (glabrous 
form) by C. de Candolle. 
5 C. de Candolle, Ann. du Conserv. et Jard. Bot. Geneve, 1898, p. 276. 
6 C. DC., Linnaea, xxxvii, p. 366. 
