10) AMERICAN MIDLAND NATURALIST 
have found out the simple facts had he sooner taken up the study 
of their habitat. He claims that he had found these two phases 
of the plant—though he does not call them such,—on the same 
rootstock,—‘‘in eadem individua.”” In every respect does he give 
the habitat of the two stages of the plant even describing the 
circumstances that lead to the change of the aquatic to terrestrial 
that is, by drying up of the pools, not a rare circumstance, and the 
casting up of the roots from ditches, and that then the leaves 
become “hirsute rough and spotted liké a Persicaria*.” He says 
even that certain authorities whom he quotes, though they consider 
these phases as different plants, yet they thought them both Per- 
sicarias, 
That Linnaeus himself knew of the amphibious nature of the 
European plant is evident from the following taken from the Flora 
Suecica of 1745. 
“318. PERSICARIA floribus petandris digynis corolla staminibus 
breviore. 
Persicaria florum staminibus quinis corollam superantibus, 
stylo bifido. Hort. Cliff. 216. Persicaria major amphibia, radice 
perenni. Pluk. alm. 288. 
Potamogeton salicis folio Bauh. pin. 193. 
(2. Persicaria palustris fluitans, foliis brevioribus et latioribus 
florum spica purpurea compactiore. Rupp. jen. 72. 
Habitat a ubique erecta in pratis argillosis juxta vias et agros 
at 3 fluitans in fossis et paludibus; singulart varvetate.”’ 
It is evident from the above that Linnaeus referred to the 
floating plant which he calls variety 0 of Ruppius asa mere variation 
of the rough terrestrial form, a. It is also evident where he gets 
his trivial name P. amphibia of the Species Plantarum of 1753. 
It is borrowed from Plukenet’s description quoted above. Another 
fact worthy of notice is that in the Species Plantarum of 1753 and 
subsequent editions he no longer considered the floating form as 
even a variety, but in view of the fact that Ray had found that one 
changed spontaneously into the other according to habitat, Lin- 
naeus suppressed entirely the varietal standing of the phases well 
* Reference probably is made to Persicaria maculosa or Polygonum 
Persicaria Linn, : ‘ 
{ Linnaeus, C. Flora Suecica, 1745, p. 115. 
