sect, ii PHANEROGAMIA 517 



The majority of Lauraceae are trees with elliptical, entire leaves 

 and small inconspicuous flowers aggregated in heads or panicles. 

 The fruit is a berry or drupe, and is often surrounded at the base by 

 the persistent receptacle. All parts of the plant contain, as a rule, 

 ethereal oil accumulated in special cells. 



Geographical Distribution. — To the Lauraceae belong many of the most im- 

 portant trees of the warmer countries of both hemispheres ; the order is almost wholly 

 unrepresented in the Temperate Zone. Europe possesses but one species, Laurus 

 nobilis, Sweet Bay (Mediterranean), a small evergreen tree with white flowers 

 clustered in axillary, capitate inflorescences. The flowers, which are dimerous, and 

 have bilocular anthers, produce a drupaceous fruit. The only herbaceous genus is 

 Cassytha, a widely distributed tropical group of parasites, resembling the Dodder 

 in appearance and habit. 



Officinal. — The fruit, Fructits Lauri, of Laurus noUlis ; the bark and wood, 

 Sassafras, of Sassafras officinale (a dioecious, deciduous tree of North America) ; 

 the gum, Camphora, obtained from Oinnamomum Oamphora (an evergreen tree, 

 native of China and Japan) ; the bark, Cortex Cinnamomi, of Oinnamomum Cassia 

 (a shrub of Southern China), and of the Cinnamon-tree, Oinnamomum zeylanicum 

 (Ceylon). The latter is no longer officinal in Germany. 



Order 6. Rhoeadinae 



Flowers hypogynous, hermaphrodite, predominantly DIMEROUS. 

 Perianth consisting of three two- or four-merous whorls ; androecium 

 of two two-merous whorls; gynoecium dimerous, syncarpous; ovary 

 UNILOCULAR, with PARIETAL PLACENTA. Herbs with alternate, simple 

 leaves without stipules. 



The Rhoeadinae constitute in themselves a natural, sharply defined 

 order, and apart from the slight resemblance displayed in some 

 instances to the Nymphaeaceae they exhibit no marked affinity to other 

 groups. The type of the order is best represented by the genus 

 Hypecoum, in which the flowers are constructed throughout of simple 

 dimerous whorls. In the largest families of the order, the Oruciferae 

 and Capparidaceae, the corolla is tetramerous, alternating with the two 

 decussate whorls of the calyx. It is often assumed, but without 

 confirmatory evidence, that in such cases the four petals are derived by 

 duplication from a dimerous corolla. The greatest variation is shown 

 by the androecium, which, in consequence of the multiplication of its 

 members, or more rarely of the whorls, frequently consists of more 

 than four stamens. Even in such cases the derivation from the 

 typical structure is generally recognisable. In the Capparidaceae, the 

 successive processes in the evolution of the andrcecium are particularly 

 apparent ; in this family, all transitions occur from a 2 + 2-merous 

 androecium to one that has become polymerous by repeated splitting ; 

 a reduction of the androecium to one whorl is also exhibited by some 

 members of the family. The gynoecium usually remains dimerous ; 



2 Q 



