170 BOTANICAL GAZETTE 
simply fundamental tissue which has been inclosed by the gradual 
curving around of the edges of the cotyledonary gap until they meet; 
moreover, the stele is in open communication with the cortex in the | 
basal region of the tuber. It has been shown that in Symplocarpus _ 
the internal phloeoterma undergoes a more or less early degenera- 
tion, so that the included parenchyma comes to lie next to the xylem, 
‘and so might be mistaken for stelar tissue in the upper part of the 
stem. 
It is of interest to note that from a general morphological study _ 
of Araceae ENGLER (1) places Acorus among the most primitive 
genera of the family, and members of the Aroideae, such as Arum 
and Typhonium, among the most highly developed of the family. 
My observations on the seedlings accord in the main with ENGLER'S 
classification; the young stem of Acorus possesses a simple stele, while 
members of the Aroideae early acquire the most complicated vascular 
system found in the family. C 
LILIACEAE. | 
In this family over fifty species have been studied, representing all 
the large subfamilies; in most cases both the adult plants and seedlings # 
have been examined. The search for primitive typés has convinced Z 
me that ancestral characters are most likely to be preserved ina — 
rhizome, since such a stem is free from the modifying influences ofan 
aerial life; hence the first subfamily to be treated is one in which most 
of the members have the basal portion of the stem a rhizome. ae. 
Asparagoideae—CrnTontA BOREALIS. —The plant is characterized ; 
by a horizontal rhizome which turns upward at the end, bears 
number of scales and several foliage leaves, and terminates in a Scape 
carrying an umbel of flowers. Fig. 13 represents a cross se a 
through the rhizome a short distance before it turns upward; fis 
be seen that the stele forms a tube perforated at the point of S a 
several leaf traces, also that there are no medullary bundles. Fig. 14 
is a more highly magnified view of a portion of the stele. It _ 
that an internal as well as an external phloeoterma is present, oo 
that these are continuous through the foliar gap; also that some 
the meristeles are amphivasal. ; 
CLINTONIA UMBELLATA.—A cross section through the rhizome 
shown in jig. 15; two foliar gaps with their traces are to be = 
