500 PART IV. CLASSIFICATION. 



SERIES II. EPIGYK2E. 

 Ovary inferior. 



Cohort I. Hydrales. Order 1. HYDROCHARIDACE.E. 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 andrcecium 

 and gynseceurn ; formula A~3, C3, AS + 3 + , G (3+ ...).- The flowers 

 are usually unisexual and dioecious ; the ? flowers have stami- 

 nodia ; the $ flowers have no gynseceum but an increased number 

 of whorls in the androecium. Seeds generally numerous ; without 

 endosperm. Water-plants. 



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

 small leaves. 



Elodea (Anacharis) canadensis 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. 



Valiisneria 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 fertilize the ? 

 flowers ; the fruit ripens under water. 



Fam. 3. 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 II. Dioscoreales. Flowers regular : floral formula 

 A'3, (73, A3 + 3, G^ : fruit a berry or a capsule : endosperm oily. 



Order 1. DIOSCOREACE^E. The ovary is trilocular, with one or 

 two ovules in each loculus : the flow r ers are dioecious. They are 

 climbing plants, with twining stems, having large above- or under- 

 ground' tubers, and usually triangular leaves with reticulate vena- 

 tion. 



Dioscorea saliva, Batatas, and others, known as Yams, are largely culti- 

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

 Tamus communist, the Black Bryony, is common in England. 



Order 2. BROMELIACE.E. K3, C3, AS + 3, G (3). The ovary is 

 superior, inferior, or semi-inferior, trilocular, with many seeds. 



