630 



PART III. THE CLASSIFICATION OF PLANTS. 



red; fruit a septifragal capsule. Circtea lutetiana (Enchanter's Nightshade) has 

 dimerous flowers jK"2, (72, A2, 0$ (Fig. 323 B) ; common in damp and shady 

 spots. Isnardia palustris has no corolla ; its fruit is a septicidal capsule. 

 Fuchsia (Figs. 429 A, 323 A), many species of which are cultivated as 

 ornamental plants, is a native of South America ; fruit a berry. 



Trapa natans, the Water-Chestnut, a not very common water-plant of Central 

 Europe, has a stem bearing a rosette of leaves which float on the surface of the 

 water ; in the axils of these leaves the flowers are borne singly : their formula 

 is K4, (74, 44, G* 2 ), and they are perigynous : the fruit is indehiscent, and the 

 sepals remain adherent to it in the form of four horns : it contains two seeds. 



Order 2. HALORAGIDACEJI. Flower sometimes monosporangiate, 

 epigynous, usually tetramerous throughout ; stamens often in two 

 whorls, and then obdiplostemonous : sometimes the corolla or the 

 whorl of stamens opposite to the petals is wanting : ovary 



1-4-merous, with a single sus- 

 pended ovule in each loculus; 

 seed containing endosperm. 



JHyriophyllum verticillatum and spi- 

 catum, the Water-Milf' ils, are aquatic 

 plants with finely divided leaves and 

 small, generally diclinous, flowers 

 borne above the water in terminal 

 spikes. 



The genus Gunnera includes land- 

 plants with large leaves : the flower is 

 dimerous, but is frequently reduced by 

 the suppression of the corolla, or of 

 one of the series of sporophylls (diclin- 

 ous) : the dimerous ovary produces but 

 a single ovule. 



The genus Hippuris consists of the 

 single (British) species H. vulgaris 



the Mare's-tail. It is an aquatic plant, bearing its very much reduced flowers 

 singly in the axils of the whorled leaves : there is no corolla, and the calyx is> 

 rudimentary : there is a single epigynous stamen, and a mononaerous ovary 

 containing a single suspended anatropous ovule. 



Order 3. LYTHRACEJE. Flowers perigynous, with usually both 

 whorls of stamens : formula Kn, (7n, | An + n, G^M), where n = 3 16 : 

 ovary free in the hollow receptacle : an epicalyx formed by connate 

 stipules is often present : seed without endosperm. 



Lythrum Salicaria, the Loosestrife, occurs in bogs and ditches : flower 

 usually pentamerous or hexamerous : the stamens of the two whorls are unequal 

 in length, and the length of the style also varies ; three forms of flowers are 

 thus produced (trimorphism ; see p. 455) : the other British genus is Peplis ; 



FIG. 430. Part of a flowering stem of 

 Hippuris vulgaris. The leaves are cut away. 

 (After Sachs.) 



