252 SYSTEMATIC BOTANY 



tube is closed by five tufts of hairs between the stamens. 

 The fruit of the Hound's-tongue is provided with recurved 

 hooks, as is also the calyx of the Forget-me-not, which 

 serve as a means of fruit-dispersal by animals. 



Order Tabiatae. Stem square ; leaves opposite ; flower 

 zygomorphic. Sepals five, united. Petals five, united, 

 two-lipped. Stamens usually four, two long and two 

 short (didynamous), epipetalous. Pistil of two carpels, 

 superior, syncarpous, each carpel divided into two cells. 

 Ovary four-lobed, with the style springing from the 

 base (gynobasic). Fruit usually four nutlets (Fig. 172) . 



There are about 150 genera and 2,800 species in this 

 order. They are very frequent in the Mediterranean region, 

 where many shrubby forms occur which are xerophytes 

 with heath-like habit and back-rolled, hairy leaves. Many 

 are scented, due to volatile oils secreted by epidermal 

 glands, and are often cultivated and used as condiments, 

 or for their oils or perfumes, e. g. Lavender (Lavendula 

 vera), Rosemary (Rosmarinus officinalis), Thyme (Thymus 

 vulgaris), Mint (Mentha viridis), Peppermint (M. piperita), 

 Marjoram (Origanum vulgar e), Garden Sage (Salvia offici- 

 nalis). 



Vegetative reproduction is common, as in the Garden 

 Mint. The square stem and opposite decussate leaves are 

 very characteristic. The primary inflorescence is usually 

 racemose, but the later branches are cymose. In some, 

 condensed cymes occur at the nodes and, overlapping the 

 leaf-axils, give rise to false whorls of flowers called verti- 

 cillasters (Fig. 172, 2). The flowers are adapted chiefly to 

 bees (Fig. 172, 3), and some to moths and butterflies. The 

 simpler flowers with shorter tubes, e. g. Thyme and Gipsy- 

 wort, are visited by miscellaneous insects. The Henbit- 

 Deadnettle (Lamium amplexicaule) produces cleistogamous 

 flowers. 



