674 



BOTANY 



PART II 



typically hexamerous with two inferior carpels. Heterostyled with three forms of 



flower (cf. p. 560). 



Family 4. Onagraceae. Flower tetramerous throughout. Androecium obdiplo- 



stemonous. Epilobium, Willow-herb, with numerous species ; the fruit is a 



capsule, and the seeds have hairs serving for wind-dispersal. Oenothera (Fig. 715). 



The power of mutating possessed by plants of this genus was recognised by DE VRIES 



and forms the experimental 

 basis of his hypothesis of muta- 

 tion. Circaea, Enchanter's 

 Nightshade. Trapa, Water 

 Nut. Many forms are in culti- 

 vation, for instance the species 

 of Fuchsia, in which the calyx 

 is petaloid. These plants are 

 natives of America. Fruit a 

 berry. 



Family 5. Rhizophoraceae. 

 Plants occurring in the Man- 

 grove formation along tropical 

 coasts, characterised by vivipary 

 and the possession of stilt- 

 roots, or respiratory roots (Fig. 

 189). These adaptations are re- 

 lated to the peculiarities of the 

 situations in which the trees 

 grow. Rhizophora (Fig. 716) ; 

 JBruguiera ; Ceriops. Kandelia, 

 (Fig. 581). All occur on the 



FIG. 714. Daphne Mezereum ( nat. size). 

 OFFICIAL and POISONOUS. 



FIG. 715. Floral diagram of OenotJiera 

 (Onagraceae). After NOLL. 



coasts of the Indian Ocean. Species of Rhizophora are more widely distributed 

 on tropical coasts. 



Family 6. Myrtaceae. Evergreen shrubs or trees ; leaves opposite, 

 leathery, often aromatic. Flowers actinomorphic, tetramerous or 

 pentamerous. Androecium of many stamens, which are often arranged 

 in bundles which have originated by branching. Carpels two or 

 many (Fig. 717) united with the floral axis to form the inferior ovary. 

 Fruit, usually a berry or a capsule. 



Mainly distributed in tropical America and in Australia. 



The Myrtle (Myrtus communis), which occurs in the Mediterranean region, is 



