Tubiflorce. 163 
identical with that typical of Verbenaceae. Fruits of this type do 
not occur in Multiovulatae ; and seeing that the schizocarpic ten¬ 
dency is here regarded as a fundamental principle of distinction 
between Multiovulatae and Diovulatae, we must regard Myoporaceae 
as a member of the latter group. They may thus represent the 
earlier progeny of the Diovulatae-stock, prior to the establishment 
of a fixed and definite number of parts in the fruit. 
There remains for consideration the largest and most advanced 
family of Diovulatae, Labiatae. This family is of world-wide 
distribution, in contrast to Verbenaceae, most of which are confined 
to tropical or sub-tropical regions; and with very few exceptions 
these are herbaceous. The ovary is typically four-celled and four- 
lobed, the latter more or less deeply; the resulting fruit is the 
familiar schizocarp of separate one-seeded nucules. It is chiefly in 
the character of the ovary and fruit that Labiatae differ from 
Verbenaceae critically ; but their distinction from the aspect of 
special evolutionary advance is marked enough. The lines of 
advance upon the ancestral stock typified in Verbenaceae find 
expression first, in the establishment of the herbaceous habit with 
its very characteristic external features—square stems, decussate or 
whorled leaves, aromatic odour, etc.; and second, in the aggregation 
of the flowers into dense inflorescences. The latter condition, fore¬ 
shadowed already in Verbenaceae, is the rule rather than the 
exception in Labiatae, and is illustrated in the common but peculiarly 
labiate type of cymose cluster known as the verticill aster. Close, 
involucrate capitula are not uncommon. 
The corolla ranges from sub-regular to strongly and elaborately 
zygomorphic, and from very small and inconspicuous to fairly large 
and brightly-coloured types. But conspicuousness is, of course, 
attained fundamentally by aggregation (supra). The androecium is 
usually tetrandous and didynamous ; in 22%, only, are the flowers 
diandrous. Staminodes are not common, and are small when 
present. Payer (loc. cit. pp. 553-557) records his investigation of the 
floral development in Stachys recta, Lavandula densa, Perilla arguta, 
Salvia patens. In all these cases five staminal primordia appear, 
successively, in an anterior to posterior direction. In Stachys the 
posterior stamen aborts almost as soon as it appears; in Lavandula it 
persists for a time. In the diandrous Salvia the laterals abort as 
well, and only the two highly-complicated anterior stamens remain. 
The Labiatae are clearly a very natural group and represent 
the highest terminal point of evolutionary progress for the Diovulatae, 
