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OF TAXODIUM DISTICHUM AND RELATED SPECIES 385 
peculiar aspect. This character, however, is not constant, and the 
variety can scarcely be maintained, the same individual producing 
during the earliest stages of growth and on vigorous adventitious 
shoots leaves of the ordinary form. This form passes freely into 
the species where the soil conditions are more favorable.’’ 
But, notwithstanding the opinions of these eminent botanists, 
it seems to me that the intergradation is more apparent than real, 
and that this idea may have arisen from a too hasty generalization 
of observed facts. It is true that young shoots of 7. imbricarium 
often bear branchlets with distichous leaves (perhaps indicating its 
descent from an ancestral form which resembled 7. distichum of 
the present day), but on the typical T. distichum 1 have seen only 
one kind of branchlets. 
The opinions of Nuttall and Croom, both of whom seem to 
have been very acute observers, are more favorable to my view of 
the distinctness of the two species under consideration. 
Nuttall, in the original description of 7. imbricarium, says: 
‘‘ Leaves subulate, partly imbricated in four ranks, deciduous ; nuts 
larger, chestnut colored.” * * * “A smaller tree than the pre- 
ceding, often producing fruit at a height of three feet from the 
ground.”’ 
Croom, in his flora of Newbern above mentioned, says (page 
48) : “ Taxodium distichum. * * * Elliott expresses the opinion that 
the variety zmbricarium of Nuttall is only this species in a starved 
condition, as it is commonly found in pine-barren ponds. But in 
some instances (20 miles above New Bern) I have seen large trees 
of this variety, and, in one instance, I observed it growing by the 
side of the common variety, and in the same soil.”’ 
The differences between the two species will now be considered 
More in detail. These differences are of several kinds, not only 
structural but ecological as well. 
The most conspicuous structural difference, as noted by most 
of the authors just quoted, is in the form and position of the 
leaves and the branchlets which bear them. In 7. distichum, as 
is well known, the leaves are two-ranked on the branchlets, widely 
Spreading, and in the same plane, making each leafy branchlet 
resemble a pinnate leaf (to which it is indeed analogous) ; and the 
branchlets spread approximately horizontally, bringing the surfaces 
