VOL. XII. NO. 5.-BOTANICAL GAZETTE MAY, 1887. 
Our “tripetalous”’ species of Iris. 
SERENO WATSON. 
A century has not been time enough for American botan- 
ists to become acquainted with two of the most peculiar of 
their species of Iris, to say nothing of other eastern species, 
which, after an even longer time, still remain only imper- 
fectly known, some of them almost unknown. 
In 1788 Walter described with unusual fullness his /. 
iripetala, of which nothing more was learned until the time 
of Elliott (1816). As there had been a prior /. éripetala of 
Thunberg, Walter’s name was changed by Pursh to /. ¢rz- 
dentata, but it was restored by Elliott, the African species 
having been transferred to JZor@a some years before the date 
of Pursh’s Flora, where ‘it still remains. There is no rea- 
son why Walter’s name should not hold good, in which 
case Pursh’s falls wholly to the ground. Elliott knew the 
species only as growing in the ponds of St. John’s an 
Stephen’s parishes, South Carolina, where Walter had found 
it. Its range has since been extended from the low districts 
of North Carolina to Florida. The only figure that has been 
given of it is as JZ. tridentata, Pursh, in Sweet’s British 
Flower Garden (1828), t. 274, from plants which had been 
recently introduced from North America and cultivated at 
the Fulham Nurseries. The figure is a very good one and 
answers closely to Walter’s description. EADS 
n the next year there appeared in Curtis’s Botanical 
Magazine (t. 2886) a figure, and a description by Sir 
- Hooker, of an Iris under the name of /. érpetala, Walt., 
said to have been communicated by David Falconer from 
his collection at Carlowrie, Edinburg, but without indication 
of its original source. It is evidently a different plant from 
that figured by Sweet, and represents fairly, so far as the 
ower is concerred (but with broader leaves and much larger 
Spathe), what we now know as a peculiar Canadian species. 
This Mr, Falconer, as appears from Loudon’s Gardener's 
uagazine (1827), had in cultivation 2 very full collection of 
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