TubifLorce. 
i55 
The suggestion has been advanced that this branch with its 
tendencies to epigyny and syngenesis of anthers may have given rise 
to the higher groups with inferior ovary, or at least to some 
portion of them ; but it must be remembered that the stock in 
question is essentially oligomerous in the androecium, while the 
“ Inferae ” are isomerous. 
We turn now to an extensive family of high specialization and 
complexity, the Acanthaceae. Alone of the Multiovulatae does this 
family at all approach Scrophulariaceae in point of number of 
species, comprising as it does rather more than three-fourths 
of the number of species in the latter. The Acanthaceae are 
mostly shrubby or suffruticose ; some are herbaceous, but trees 
are rare. They are extremely common in tropical regions, where 
they constitute the greater part of the weedy vegetation ; very few 
are extra-tropical. 
The distinctive characters of the family are concerned with 
conspicuousness of both the individual flower and the inflorescence, 
with anther-specialization, and with seed-distribution. The inflor¬ 
escence, often spicate, is typically associated with conspicuous and 
often highly-coloured bracts. The flowers are, relatively speaking, 
generally large—as compared, for instance, with those of Scrophu- 
lariaceae. The corolla is frequently strongly zygomorphic, often 
elaborately bilabiate ; at the same time sub-regular corollas with 
lobes almost equal are by no means uncommon, especially in 
those forms which are in other respects relatively primitive. 
The androecium displays marked advance. It is anisoste- 
monous almost without exception ( Pentstemonacanthus ). In about 
40% of the species, the stamens number four ; in 15%, four or two; 
while in about 45% the androecium consists constantly of two 
stamens only. In the more advanced forms ( e.g ., Justicieae) the 
anthers are variously modified, doubtless in relation to pollination, 
although the details are practically unknown in most cases. A 
common form of modification consists in the inequality and 
sterilization of one of the anther-cells, which may become 
elaborated in various ways. 
Staminodes are of common occurrence, especially in the 
flowers with only two stamens; in the tetrandrous flowers, 
however, the posterior stamen is rarely represented in any form. 
According to Payer, five primordia are invariably present in the 
young androecium of Acanthus mollis, but the posterior one aborts 
at a very early stage. 
