20 BULLETIN 272, U. S. DEPARTMENT OF AGRICULTURE. 
headings. Each of the two forms, however, within itself presents 
real variations in leaf, branch, bee and or 
There are indienne that ae Sel form (var. wmbricarwwm), 
which is more abundant over the Atlantic Coastal Plain than else- 
where, is undergoing a gradual botanical segregation durmg its 
assumed northward migration from Florida, and has been since 
the close of the glacial period. Progress in segregation is necessarily 
slow on account of the heaviness of the seed and its exacting moisture 
requirements for successful germination. Evidence points clearly 
to soil conditions, particularly acidity and drainage, as fundamental 
factors causing the botanical variation of cypress. The range of 
the imbricate form, so far as at present known, is generally coincident 
with the limits of the Atlantic Coastal Plain, but extends southward 
into northern Florida and westward to Alabama. The main species, 
on the other hand, finds its most congenial home along the Gulf 
Coast and up the Mississippi Valley in the deep alluvial soils. 
OCCURRENCE. 
The close restriction of cypress to very wet situations suggest 
two explanations: (1) That the species requires much water and is 
in reality a semiaquatic or mud-inhabiting species, or (2) that it 
has been forced to these unfavorable situations because of inability 
to compete with species better adapted to occupy the more favorable 
uplands. 
Close observations on young cypress agree in furnishing evidence 
that, in its early stages, cypress is very exacting and successfully 
establishes itself only in situations of very abundant moisture. 
Subsequently, however, seedling growth is noticeably more rapid 
on better drained situations. These observations lead to the con- 
clusion that in extremely wet situations cypress, in a greater or 
less degree, is tolerating conditions not generally favorable to the 
normal thrifty growth and development of the tree. In other 
words, the inherent soil and moisture requirements of cypress after 
its earliest stages are to be looked upon as very similar to those 
of many of the hardwood timber trees which thrive best in a deep, 
loose, well-drained, fresh, rich, sandy or clayey loam, containing 
humus and available mineral food, and well supplied with soil 
moisture. 
Broadly speaking from a geological standpoint, cypress therefore 
belongs characteristically to young lands. Cypress is the dominating 
tree in the forests of the alluvial lands of the South. It advances 
slowly, but ahead of all other trees, as river and sea marshes gradually 
build up, flourishes in the deep alluvial souls submerged for a portion 
of the year, and later is driven out by the competition of hardwoods 
as the lands are further built up and become drained. 
