[ 43i 3
T U S S I L A G O Petafites*
Common Butter-bur.
S Y N G E N E S I A Polygamia-fuperjtuct.
G e n . C har. Recept. naked. Down limple. Calyx-
fcales equal, as long as the difk, fomewhat membranous.
S p e c . C har. Panicle denfe, ovate. Flowers almoft
all hermaphrodite, with united antherae.
S y n . Tuffilago Petafites. Linn. Sp. PI. 1215. Hudf.
FI. An. 364. With. Bot. Arr. 906. ed. 3. v. 3.
720. Relb. Cant. 314. Sibth. Ox. 261. Curl.
Bond. fafc. 2. 1. 59.
Petafites. Rail Syn. 179.
VV
E R Y common on the banks of rivers and in mold fhady
places, flowering in April, about which time alfo the leaves
appear, and in the courfe of the fummer grow to a great fize,
being 2 or 3 feet in diameter.
_ T h e root is perennial, creeping very far, and increafing rapidly,
fo as to be extirpated with difficulty$ in which refpeCt it
agrees with T . hybrida, as well as in the appearance and form
o f its leaves, which however are fomewhat larger in the Petafites.
T h e flower-ftalk differs chiefly in being rather fhorter,
and the panicle after flowering lefs lengthened out. T h e flowers
are larger, and fcales of the calyx twice as long. A ll the florets
are hermaphrodite in appearance; but their ftigmas are thick
and barren, many authors obferving that the feeds are never
perfected. T h e younger Linnaeus and Haller, however, have
occafionally noted a very few female florets to accompany the
others, which the latter tells us produce good feeds. T h is
eircumftance is rare, and has not been obferved in England j
nor, i f general, would it invalidate our conjecture, that this
is the real male o f T . hybrida, forming but one fpecies with
that. It is worth confideration whether the T . alba may not
ftand in the fame relation to the paradox a o f Retzius, Ait. Hort.
Kew. v. 3. 188. T h e antherae o f T . Petafites are united, as
in alba in paradoxa, as in hybrida, they are feparate. All thefe
plants increafe fo much by root, that impregnation (whether
in the fame individual or not) rarely takes place, which is
alfo the cafe with mints and many other vegetables. W e agree
with D r . Stokes and Profeffor Sibthorp, that as the florets o f
the circumference only in this genus produce perfect feeds, the
central ones having the thickened ftigma which appears always
to be barren, it might be removed to the order o f Polygamia-
neceffaria; but Syngenefious plants are fubjeCt to fuch variations
in the perfection o f their organs o f impregnation, that it is by
no means certain how far that order, or indeed fome others,
are founded in nature. This point we cannot here difcufs, but
may on fome future occafion.