D1COTYLEDONES : POLYPETAL2E : CALYCIFLORJ!. 



629 



Mamillaria has a spherical or cylindrical stem on which tubercules, arranged 

 spirally and bearing spines, represent the leaves. Echinopsis and Echinocactus 

 have angular ridges on which the tufts of spines grow. Cereushas an angular, 

 columnar, elongated stem. Phyllocactus and Ehipsalis have compressed leaf- 

 like stems. Opuntia and Nopalea have flattened stems composed of a suc- 

 cession of flattened ovate shoots. The Cochineal insect lives on Nopalea cocci- 

 nellifera. 



Cohort III. Myrtales. Flowers usually actinomorphic, 

 encyclic, epigynous or perigynous, with usually two whorls of 

 stamens, typically obdiplostemonous : gynaeceum syncarpous, with 

 usually a single style : leaves usually opposite. 



PIG. 429. A Flower of Fuchsia: pedicel ; / inferior ovary; fc sepals, connate at the 

 base, forming a tube (r) ; a stamens ; g style ; n stigma. J5 Flower of Epilobium hirsutum 

 (letters as before). C Fruit of Epilobium after dehiscence; w outer wall; m columella 

 formed by the septa ; sa seed with tufts of hairs (nat. size). 



Order 1. ONAGRACEJ;. Flowers usually tetramerous throughout, 

 generally epigynous : antipetalous stamens sometimes suppressed : 

 ovary multilocular, with generally numerous ovules on axile 

 placentae: fruit a berry or a capsule; seed without endosperm. 

 Calyx often petaloid, forming a long tube (Fig. 429 A, r). 



(Enothera biennis, the Evening Primrose, occurs on river banks ; the seed has 

 not a tuft of hairs, and the flowers are yellow. Epilobium is the Willow Herb, 

 of which many species are common ; E. angustifolium, hirsutum, aod montanum 

 occur in fields, hedges, and ditches ; the seeds have a tuft of long hairs ; flowers 



