180 THE REV. б. HENSLOW ОМ THE ORIGIN OF FLORAL ASTIVATIONS. 
B. VALVATIVE. 
7. Valvate (including varieties). 
Calyx valvate, with Corolla various. occurs about 11 p. c. 
Corolla valvate, with Calyx various. 5 > 
8. Straight or open. 
Calyx open, with Corolla various 8 25 75 
Corolla open, with Calyx various . a os 
II. Petaloid Monocotyledons. 
1. Equitant is represented in 3 genera 
only besides Grasses. 
2. Tristichous, outer perianth whorl . . ў 40 ,, 
Re inner perianth whorl . . 5 60 „ 
8. Pentastichous occurs in Paris polyphylla, p. 859. 
6. Convolute, represented in 4 genera only. 
КИ a S c 3 20-24 
oc ш їп. аза e 5 80 «5, 
IV. REMARKS ON THE PRECEDING VARIETIES OF /ÉSTIVATION. 
1. Equitant.—The proportion of flowers which have equitant whorls, either entirely, 
when one member of the pair is embraced by both the edges of the opposite member, or 
half-equitant, in which each of the pair overlaps one edge of the other, occurs in corollas 
about 12 р. с. and in calyces about 4 р. с., as calculated from the diagrams of Le Maout 
and Decaisne. Probably this is not far from being correct. 
With regard to the origin of this kind, I am inclined to think it is due to a reduction 
of parts from the tristichous or pentastichous arrangements, and in some cases may be a 
retention of a primitive condition. If one member of а tristichous whorl be suppressed, 
the other two will most probably become equitant, as flowers almost * invariably arrange 
their members either radially or bilaterally symmetrically. Such, I suspect, will account 
for this sstivation in poppies, for example, where the calyx is half-equitant and the 
corolla equitant (Tab. XXV. fig. 1). Papaver and its nearest allies of the tribe 
Eupapaveree are usually binary or quaternary in their perianths, though whorls of 
threes are not wanting, and seem to point to their ancestral character, which is retained 
in Romneyee@. Moreover Papaver orientale not unfrequently develops a third smaller 
sepal, which may or may not be accompanied by a trimerous corolla, which I take to be 
due to atavism. 
If this theory be correct, the ancestors of poppies were trimerous ; but by the arrest of 
one part in the calycine and one in each of the corolline whorls, these have become 
dimerous and equitant in zestivation. 
р ety А e rare instances, due to insect agency, such as Polygala chamæbuxus and Phaseolus, which аге, 
во to say, “ distorted.” І use the word symmetrical here in its popular, not botanical sense, as usually restricted, 
though Sachs applies it thus. The term zygomorphic has been used to express bilateral symmetry, and, if вепе- 
rally adopted, would avoid much confusion. 
