_ Taxodium distichum and related Species, with Notes on some geo- 
logical Factors influencing their Distribution 
By RoLtanp M. HARPER 
Observations on the genus 7axodium in the field during three 
or four seasons have led me to the conclusion that there are at 
least two well-marked species in the southeastern United States. 
Most authors who have written on the subject have considered the 
genus to be represented in that region by a single species, but 
some have admitted the existence of a variety in addition. 
The genus was founded by L. C. Richard in 1810, with a 
Single species, the Cupressus disticha of Linnaeus; and the num- 
ber of living species in the world has since been variously re- 
garded as from one to three, excluding species which are now 
referred to Seguoia and Gly ptostrobus. 
Before discussing the relationships of the two southeastern 
Species it will be well to give their principal synonymy, which is 
as follows : 
TaxopiIum pisticHuM (L.) L. C. Richard, Ann. Mus. Par. 16: 
298. 1810 . 
Cupressus disticha LL. Sp. Pl. 1003. 1753. Type locality: 
“ Virginia, Carolina.” 
Schubertia disticha Mirbel, Mem. Mus. Par. 13: 75. 1825. 
Taxodium imbricarium (Nutt.) 
Cupressus disticha 8 imbricaria Nutt. Gen. 2: 224. 1818. 
Type locality: “From Florida to North Carolina, in swamps 
and ponds more remote from the sea.” 
Laxodium ascendens Brong. Ann. Sci. Nat. 30: 182. 1833. 
Type locality North American, but not specifically given. 
_L. distichum var. imbricarium Sarg. Sylva N. A. 10: 152. 
18096. 
The latter form of the name was used by H. B. Croom in his 
Plants of New Bern (now Newbern), N. C., in 1837, by M. A. 
Curtis in his flora of North Carolina in 1867, and by Wood & 
_ McCarthy in their Wilmington (N.C.) Flora in 1886, but does: 
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