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AMERICAN JOURNAL OF BOTANY 
[Vol. 8 
abietifolia). Here, extending over more than a year in 1885-6, flowering 
and dying down were general; this occurred again in 191 9, when 98 percent 
of the plants formed the dead entanglements, and the young plants 18 
inches high covered the ground in long stretches (as recently described in 
this Journal). 2 A rough thirty-three-year period is indicated, with only 
minor or suppressed seasonal factors. 
These are communal forms, and whoever has seen one of the isolated 
dead pure stand thickets of bamboo in an open hilly region, as in parts of 
southern Mexico (Oaxaca), where there is a long, dry winter period, under- 
stands that average length of life and single flowering are complementary, 
intensified habits. In such plant communities the life of the individual 
is simple, set, and tense; and as soon as a considerable number of the plants 
fruit and die down, the light, heat, moisture, and soil conditions of the copse 
change rapidly. Only the plant behaving in the average way tends to 
leave its progeny. Even in the tropics there are forms which flower over 
wide areas on precisely the same day. Then, in the forests of Pegu, certain 
orchids are seen to blossom as the limbs on which they are seated lose their 
leaves. Yet there is the remarkable variation in that some trees bloom 
quite through the year, as the mango, silk cotton, and fig. This has been 
noted especially in orchids. 
Casually, this much may be said of the monocarpic habit. Plants 
seemingly take full advantage of their environment in reaching their many 
forms. But they grow as they may, and reproduce as they must. The 
law is simple, complex though its expression may appear. Reproduction 
is sharply seasonal in the severe environment, and of more varied phase in 
the soft climate where growth factors find their favorable mean. In the 
cool temperate zones, the period of flowering varies for weeks as moisture 
and heat vary with the unusual season. In the tropics the utmost variations 
are found. Many of the woody plants are not dependent on their foliage in 
blossoming in or after the dry season. Such is the habit of various mag- 
nolias of the subtropics, and further north, where the burst of flowers is 
put forth earlier than the young leaves easily grow. These are tender and 
in our climate whipped by chill winds of early spring. Yet other trees are, 
as Schimper notes, evergreen in their flowerless youth, losing their foliage 
as they flower and fruit. Though such (Schizolobium giganteum of Java) 
suggest a certain advance toward monocarpy. 
Evidence of Monocarpic Conditions in Cycadeoids 
In few extinct plants could we hope to detect evidence for so recondite a 
feature as flower growth but once in a lifetime, or for any modified form of 
monocarpy — not even under most favorable circumstances of fossilization. 
Among all the plants of the past, the petrified cycadeoids alone present 
2 Seifriz, William. The length of the life cycle of a climbing bamboo. A striking case 
of sexual periodicity in Chusquea abietifolia Griseb. 
Amer. Jour. Bot. 7: 83-94. 1920. 
