DICOTYLEDONES : GAMOPETALJ?. 



651 



common Centaury, is common in pastures (Fig. 451). Species of Cicendia and 

 Cblora also occur in Britain. 



Sub-order 2. Menyanthe^. Leaves spiral : corolla with valvate aestivation. 



Metiymithes trifoliata, the Buck-beau or Bog-bean, with ternate leaves, is 

 common in marshes (Fig. 324 F) : Villania nymplKeoides (or Limnanthemum 

 peltatmii) is found in ponds and rivers. 



Order 2. Loganiace^. Corolla with usually valvate aestivation : 

 ovary usually bilocular, each loculus containing one or several 

 ovules: seed with endosperm (Fig. 295 A). Mostly trees with 

 opposite and usually exstipulate leaves ; some are climbers with 

 either twining stems (e.g. Fagrsea, Gelsemium), or stem-tendrils 

 (species of Strychnos), 



Semen Strychni, or Nux vomica, the seed of Strychnos Nux vomicn, in the East 

 Indies, is extremely poisonous. The South American Indians poison their 

 arrows with a substance known as Curare, in the preparation of which the 

 cortex of species of Strychnos is used. 



Order 3. Apocynacej:;. Corolla with contorted aestivation. The 

 two carpels are usually connate only by their styles, which become 

 free as they ripen : seed usually devoid of endosperm. Herbs or 

 shrubs, sometimes climbers, with milky latex. 



Vinca minor (see Fig. 324 A) and other species, the Periwinkles, are common 

 creeping plants, wild and in gardens. Nerium Oleander, an ornamental shrub, 

 and species of other genera {e.g. AUamanda, Landolphia, Amsonia, Dipladenia) 

 are often cultivated : Allamanda and Dipladenia include scrambling species, 

 climbiug by means of hooks : Allamanda has a unilocular ovary with two 

 parietal placentee. 



Order 4. AscLEPiADACEi*;. 

 Corolla with usually imbri- 

 cate aestivation. The two 

 carpels usually form two dis- 

 tinct monomerous ovaries : 

 styles short, united into one 

 stigma : stamens connate, 

 forming a tube s unrounding 

 the gynaeceum, having pouch- 

 shaped (Fig. 452 A J?, t) and 

 spur-shaped (Fig. 452 A B, h) 

 appendages : anthers 2-4 

 locular ; the pollen of each 

 sac forms a mass (pollinium, see p. 434), and the masses of each 

 pair of contiguous sacs adhere (Fig. 452 0, p, p) and are conveyed 



Pig. Abl.—A Flower of Asclepias (mag.): c 

 the reflexed corolla ; n Btigma ; h the spurs, t 

 the pouches, of the stamens. B A solitary sta* 

 men; a the anther. C PoUen-maases, }> and ]>. 



