536 



DICOTYLEDONES. 



Order 4. Labiatae. The special characteristics are: the square 

 stem, the opposite leaves (without stipules), the inflorescences which 

 are formed by two double unipared scorpioid cymes, the labiate 

 corolla, the 4 didytiamous stamens (the posterior being entirely 

 suppressed) (Pig. 574), and the 4-partite schizocarp with nut-like 

 Jntitlets. The floral formula is So, P5, A5 (the posterior stamen 

 is generally absent), G2. 



They are chiefly aromatic plants (herbs, shrubs, e.g. Lavender, 

 or trees), volatile oil being formed in internal cells or in the 

 glandular hairs, which cover all green parts. The stem is 

 always more or less markedly square ; the leaves are borne 

 upon the flat sides, and are simple and penninerved, but vary in 

 the other characters. The inflorescences are double unipared 

 scorpioid cymes, which may be situated at some distance from 

 one another in the axils of the foliage-leaves (Fig. 575 ^1), but 



frequently when the subtending leaves 

 are bract-like, they are crowded into 

 spike-like inflorescences (Larandula, 

 Mentha, Salvia, etc.), each of the so- 

 called "whorls" (verticillaster, glome- 

 mlus) being a double unipared scorpioid 

 cyme (Fig. 574). (Solitary flowers are 

 found in e.g. Scutellaria, and Origanum). 

 FIG. s-i.-Diagram of j. OM1 um The calyx is strongly gamosepalous, 5- 



albuiii .- si; dichasia. 



toothed, often bilabiate (Fig. 575 B). 



The corolla is strongly bilabiate (Figs. 575, 576, etc.), with 2 

 lobes in the upper lip and 3 lobes in the under lip (an approach 

 to regularity occurs only when the upper lip is small, and thus 

 resembles one lobe, as in Mentha (Fig. 578) and Lycopits, so that 

 the corolla approaches the 4-merous corolla of Veronica and Plan- 

 t-ago). The posterior stamen in the diagram (Fig. 574*) is entirely 

 suppressed ; in most of the genera the posterior lateral stamens 

 are the smaller (Fig. 575 D), and are entirely suppressed in some 

 (see below) ; in others, e.g. Nepeta, they are the longer. 2 stamens 

 are found in Salvia, liosmarinus, Lycopns, etc. The two halves of 

 the anthers are often separated from one another, and are placed 

 at an angle with each other. The gynoeceum has 1 style with a 

 bifid extremity (Fig. 575 (7) bearing the stigma; the true bilocular 

 ovary is divided by a false partition-wall into 4 loculi, each with 

 1 erect ovule (Fig. 575 H). These 4 loculi project so strongly 

 that the ovary becomes deeply 4-lobed with the style situated in 



