630 



PART III. THE CLASSIFICATION OF PLAXTS. 



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

 dimerous flowers A'2, C2, A2, G{-i) (Fig. 323 B) ; common in damp and shady 

 spots. Ismirdia 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 nutans, 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, 04, A4, G<r>, 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. HALOEAGiDACEiE. 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. 



Myriophyllum verticillatum and spi- 

 catum, the Water-Milfoils, 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 monomerous ovary 

 containing a single suspended anatropous ovule. 



Order 3. Lythrace^. Flowers perigynous, with usually both 

 whorls of stamens : formula Kn, Cn, | ^n + n, G'^*, where n = 3 — 16 : 

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

 stipules is often present : seed without endosperm. 



Ly thrum 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 

 Hipimris vulgaris. The leaves are cut away. 

 CAfter Sachs.) 



