560 PART III. THE CLASSIFICATION OF PLANTS. 



SEEIES II. EPIGYKE. 

 Ovary inferior. 



Cohort 1. Hydrales. Order 1. HYDROCHARIDACE^;. The in- 

 florescence is at first enclosed in a spathe formed of a single bract, 

 or more commonly of two connate bracts. The flowers have a 

 perianth, the inner whorl being petaloid, and usually conform to 

 the monocotyledonous type, but with pleiotaxy in the andrce- 

 cium and gynaeceum ; formula K3, 03, A3 + 3 + , Gr (3 + ... } : The 

 flowers are usually monosporangiate and dioecious ; the $ flowers 

 have staminodia ; the <$ flowers have no gynaeceum but an in- 

 creased number of whorls in the andrcecium. Seeds generally 

 numerous ; without endosperm. Water-plants. 



Fam. 1. Hydrillece. Ovary unilocular. Stem elongated, with whorls of 

 small leaves. 



Elodea (Anacharis) canademis came originally from North America and has 

 spread in our waters so as even to impede navigation in canals. 



Fam. 2. Vallisneriece. Ovary unilocular. Stem short, with crowded leaves. 



Vallisneria spiralis inhabits the lakes and ditches of the warmer parts of 

 Europe. The leaves are long, narrow, and linear. The ? flowers are raised 

 above water on long peduncles ; the $ inflorescences break away from their 

 peduncles and float about on the water to fertilise the $ flowers ; the fruit 

 ripens under water. 



Fam. 3. Halophilea. Perianth of outer whorl only ; ovary unilocular. 



Submerged marine plants, forming the single genus Halophila. 



Fam. 4. Stratiotece. Ovary 6- (or more) chambered. Stem short, with 

 crowded leaves. 



Stratiotes aloides (Water- Soldier) has stiff narrow leaves. Hydrocharis 

 Morsus Ranee is the Frog's Bit ; the plant is small and floats on the water, 

 with small roundly- cordate leaves. 



Cohort 2. Dioscoreales. Flowers regular : floral formula IiT3, 

 (73, .43 + 3, G (3, : fruit a berry or a capsule : endosperm oily. 



Order 1. DIOSCOREACEJ;. The ovary is trilocular, with one or 

 two ovules in each loculus : the flowers are monosporangiate and 

 dioecious. They are climbing plants, with twining stems, having 

 large above- or under-ground tubers, and usually triangular 

 leaves with reticulate venation. 



Dioscorea sativa, Batatas and others, known as Yams, are largely cultivated 

 in the tropics, their tuberous roots yielding a food rich in starch. Tamus 

 communis, the Black Bryony, is common in England. 



Order 2. TACCACEJ:. The ovary is unilocular and many-seeded. 



