THE REV. G. HENSLOW ON THE ORIGIN OF FLORAL AESTIVATIONS. 185 
in asingle projected coil or circle, which сап only arise from the series 1, 4, 2, 1, &c. 
I observe Prof. Gray also notices the mistake of those authors, which occurs also in 
other text-books. If, however, we proceed from the last-mentioned ssstivation, or the 
half-imbricate, in which the 2nd part lies nnder the 4th, and place the 3rd under the 
5th, we at once obtain the present kind. 
In the percentages deduced from the diagrams of Le Maout and Decaisne, it will be 
seen that this kind is much less common (only 9 p. c.) than the preeeding; and what 
appears true for genera is also true for flowers of individual plants. Thus Laurustinus 
and Primrose give the percentage of imbricate proper as only 10. 
6. Convolute.—As the last is derived from the half-imbricate, so this is obtained from 
the imbricate proper, by placing the 1st part under the 3rd of the quineunx ; so that if 
we write the connexion of these three kinds successively, it will appear as follows :— 
starting with the quincunx, if we place the edge of No. 2 under No. 4, we obtain the 
half-imbricate ; next, place the edge of No. 3 under No. 5, and we get the imbricate proper ; 
and lastly, in addition to these, place the edge of No. 1 under No. 3, and the convolute 
is secured. 
As long as the convoluted petals are erect and their median lines vertical there will be 
no torsion; but in some cases the apex appears as if it were artificially twisted, as in 
Mallow, Flax, «с. In these cases the word “ contorted” can be applied either with 
or without “ convolute " as well. 
In turning to the percentages deduced from the diagrams of Le Maout and Decaisne, 
it appears that in corollas of different genera the number recorded gives the convolute 
variety a position of 16 p. c.; and in comparing this with the percentages of the same 
kind, deduced from flowers of the same species, as of the Primrose, it amounts to 15 p. c., 
or almost the same. 
7. Falvate.—Of this kind of estivation, with its two varieties induplicative and 
reduplicative, little need be said. They are comparatively rare both among sepals and 
petals. With regard to the origin of it, I believe, in possibly the majority of instances, 
it is due to a degradation from the imbricative kinds, using that term in a general sense. 
It is at least probable in all instances where the flower is presumably due to a spiral 
phyllotaxis. The diagram of Geum, р. 882, appears to afford an instance of a transition 
from the quincuncial to the induplicative in the petals, while the calyx has assumed a 
reduplicative form. I have reproduced this diagram in Tab. ХХУ. fig. 18. 
In some cases where the flowers are dimerous or tetramerous, a symmetry which has 
probably risen from a similar opposition in the foliage-leaves *, it is also probable that 
no spiral arrangement has ever intervened. This may explain the fact of Clematis being 
nearly the sole genus (Naravelia is properly a subgenus only) of ри which 
has opposite leaves and tetramerous flowers with a valvate calyx. Similar is it with the 
genera of О1еасее, аз the Lilac, the sepals of Epilobium, of Rhizophora, &с. Ап illus- 
СА hope to develop this idea on a future occasion. І would just call attention to the significant fact that of the 
genera of Бовасеж, comprising 71 in all, as recorded in the * Genera Plantarum’ (Benth. and Hook.), three only 
have opposite leaves, and these three are alone characterized as having tetramerous flowers, viz. Zhodotypus, 
Eueryphia, Coleogyne. 
SECOND SERIES.—BOTANY, VOL. I. Әт 
