i5§ 
H. F. Wernham. 
herbaceous ( Argylia , Incarvillea). They inhabit the tropics, chiefly 
those of South America, where they are said to form a conspicuous 
feature of the liane vegetation. They are further exceptional among 
sympetalous woody plants in the frequent possession of compound 
leaves. We have already drawn attention to the relative rarity of 
this character among sympetalous trees, while it is quite common 
among polypetalous woody plants— e.g., Leguminosae, Sapindaceae, 
Rutacese, Meliacese, etc. We are thus led to surmise that the 
Bignoniaceae may be, relatively speaking, a primitive group, since 
its members share a conspicuous common character with Archi- 
chlamydeae ; and this finds some support in the presence of a woody 
habit among members of these higher groups, whose main tendency 
is towards a herbaceous habit (see chapters IV, V). 
Let us examine whether this surmise is justifiable; in other 
words, whether Bignoniaceae stand near the apocynal-multiovulate 
stock. The climbing shrubby habit and opposite leaves certainly 
recall Apocynaceae, and further links with that family are not 
wanting. The mode of seed-dispersal is essentially the same, 
provision being made for the individual dispersal of a large number 
of seeds from a dehiscent fruit (see last chapter); but in Bignoniaceae 
the seeds are usually winged, not comose. At the same time winged 
seeds are not altogether rare in Apocynaceae. The corolla in the 
former family is, in most cases, almost regular with a broadly open 
mouth ; irregularity rarely proceeds much further than a bending 
in the corolla-tube or the lateral facing of the flower and a slight 
obliquity of the corolla-limb. 
It is especially the andrcecium which justifies the inclusion of 
Bignoniaceae among the higher groups of Tubiflorae, for it is anisoste- 
monous. The oligomery of the stamens has, however, not pro¬ 
ceeded far; for the flower has nearly always four stamens, with 
a fifth represented by a staminode. The latter is remarkably 
constant throughout the family, the sole exception, apparently, being 
the genus Argylia. Payer found that in the developing flower of 
Bignonia grandijlora five staminal primordia are laid down ; the 
posterior stamen never becomes fertile, but persists as a simple 
filamentous staminode. 
In Catalpa (about six species in all) three members of the 
andrcecium are staminodial, only two being fertile stamens. The 
isomerous androecium, on the other hand, is equally rare, occurring 
in about seven species only ( Oroxylum , Rhigozum, Catophractes). 
The ovary is typically bilocular as in the parent apocynal 
