POLYPODIUM FALCATUM, 
SICKLE-LEAVED POLYPOD, OR LIQUORICE FERN, 
NATURAL ORDER, FILICES, 
POLYPODIUM FALCATUM, Kellogg.—Frond deeply pinnatifid, segments alternate, long lance 
falcate, alternate, acuminate, doubly serrate, upper and lower divisions smaller by degrees, 
terminating above in a long slender acumination. Sori numerous, twenty to twenty-four 
in‘two rows, one on each side of the mid-rib, rachis glabrous, from one to one and a half 
feet in height. Root compressed tuberculate, one-fourth to one-eighth inch broad, greenish 
russet color, branching laterally, radicles numerous, rhizoma often covered with scales. 
(Dr. Kellogg in the Proceedings of the California Academy of Sciences, for December, 
1854; see also Zaton’s Ferns of North America.) 
N a recent work on a curious order of water plants known 
wg] as Chara—‘Characeee Americane’”—the author, Dr. 
Allen, quotes a distinguished student of the lower orders of 
vegetation, Alexander Braun, as saying: “So long as I knew but 
few forms of the Gymopodee, their distinction was easy, but 
when it became necessary to distinguish sixteen or eighteen 
forms, I concluded to consider them all varieties of a single 
species.” This extract from one of the most celebrated of 
German botanists shows that even those who have penetrated 
the deepest into the mysteries of plant life have no definite idea 
of what determines a species. If some accident had destroyed 
all the individuals comprising a dozen of the intermediate forms, 
so as to leave only the extremes, we see that Braun would have 
regarded these extremes as distinct species; but because the 
intermediates had not been destroyed, and thus affording a 
chain of close relationships, they are all regarded as of one 
species. 
Now most botanists have had the experience with ferns that 
Braun had with Characee. The less we know of any species the 
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