DISSEMINATION AND LEAF REFLEXION OF YUCCA. 99 
the inflorescence of Yucca brevifolia as terminal: ‘‘ After 
blooming, two or three stout branches usually develop by 
the side of the original apex, which now has ended its 
growth. When these have reached a length of two or 
three feet each forms a terminal inflorescence and branches 
in its turn, giving rise to a repeated forking or triparti- 
tion.”’ * It does not appear, however, that a morphological 
examination has been made to determine this point. In 
the lack of definite information, I speak of the inflorescence 
as terminal and the buds as lateral in this paper. 
The periodical development from the base of the inflor- 
escence, of the lateral buds which continue the stem in 
aloifolia and some other Yuccas, results in forming a trunk 
consisting of a certain number of units or segments which 
are quite distinct. These may be designated ecological 
phytomers or phytomeroids.t The branches formed at the 
side of the old fruit cluster do not usually bloom the next 
spring, but spend a year in their development, bloom the 
second spring, and fruit the second fall or winter after they 
start to develop. A period of two years is thus required for 
the completion of one of the phytomeroids. No exceptions 
to this have been observed though they probably occur. 
Some plants bloom very early in the spring and mature their 
fruits early in September. It is quite probable that the 
lateral shoots of these early blooming plants may succeed 
in making a sufficient growth to bloom the next spring, 
probably rather late, and mature their fruits the next 
* Trelease, Wm., ‘‘ Further Studies of Yuccas and their Pollination,’’ 
l.c., p. 194. 
+ From phytomera (d¢utoy, plant and pepos, part) and edo¢g, form. 
Phytomera or phytomers was used by Gray (Gray’s Botanical Text Book, 
6th Ed., Vol. I., Structural Botany or Organography on the Basis of Mor- 
phology, p. 7), to designate the units of a stem, each including an internode 
and node with its leaf. 
Phytomeroid as used here is apparently equivalent to what Gray has 
called definite shoots (l.c. p. 49), and is what in German is known as 
Langtrieb, Haupttried, etc. (R. Hartig, “‘ Lehrbuch der Anatomie und 
Physiologie der Pflanzen,’’ p. 116, Pax, * Allgemeine Morphologie der 
Pflanzen,’’ p. 24.) 
