Floral Evolution. 
375 
referred to in Chapter II. Other archichlamydeous genera in which 
a corolla-tube occurs in all the species are Gomphandra (Olacacem), 
Montia (Portulacaceae), Loncliostoma (Bruniaceae), Quassia (Simaru- 
baceas), Hcdwigia (Burseraceae), Chisocheton (Meliaceae), Tapura 
(Chailletiaceae), Antholoma (Tiliaceae), Fonquicra (Tamaricaceae), 
Carica (Caricaceae), Axinandra (Lythraceae), Brachystum (Melasto- 
maceae); and the petals are united in many species of Connarus 
(Connaraceae), Loasa (Loasaceae), Opuntia (Cactaceae), Marlea 
(Cornaceae). Basal cohesion of the petals occurs more or less 
frequently among most if not all of the families referred to above, 
as also in Resedaceae (Oligomeris), Droserac ese(Byblis), Saxifragaceae, 
section C of Sapindales, 1 Vitaceae (Leca), Malvaceae, Sterculiaceae, 
and section A of Parietales (Guttiferales). Beside these are those 
quite numerous cases in which the petals cohere above to form a 
cap, a feature common in Vitaceae, Caryocaraceae, Marcgraviaceae, 
and Myrtaceae, as well as other isolated instances in which the 
petals are united throughout except at the base (e.g., Stackhousia). 
Many of these latter cases of sympetaly, however, have conceivably 
no relation or analogy to the fundamental sympetaly concerned 
with the formation of a corolla-tube in connection with insect-visits 
and the concealment of honey. 
The foregoing list includes most of the families concerned, but 
by no means all the genera ; a sufficient number of these excepta 
has, however, been quoted to give some idea of the wide area of 
relationship over which they occur. 
If Sympetalae have been derived from polypetalous ancestors, 
then we must regard the foregoing excepta as having leaped to 
sympetaly in the course of descent without advancing in any other 
character beyond those of some well-defined archichlamydeous 
group, and without acquiring such a complex of characters as 
would justify their inclusion in any known sympetalous group. 
This is the position we have adopted in regard to Cucurbitaceae. 
We now have to refer to those floral forms which have advanced 
as far as some definite sympetalous group in all characters save 
that of cohesion in the corolla, the latter having lagged behind the 
other organs in the history of the flower; these have necessarily to 
be included in Sympetalae in spite of their polypetalous corollas. 
The group which is richest in these latter excepta is Pentacyclidae 
(Heteromerae); and this is precisely what is to be expected on the 
assumption that Sympetalae are the descendants of polypetalous 
1 E.g., Ilex, including the common Holly. 
