MONOCOTYLEDONS. 



55 



tion of the central cells. The new growth springs always 

 from the centre of the stem ; it is therefore styled Endoge- 

 nous, or Inside-growing. Observe these characteristics : 



I. Covered Seeds. Embryo with radicle, plumule, and 

 One cotyledon, which sheathes the plumule ; 



II. Flowers with perfect pistils and stamens; perianth 

 usually present, and often conspicuous ; 



III. Floral parts ternary, — in threes or a multiple of 

 three (Figs. 62, 63, 64) ; rarely in twos or a multiple of 

 two (Roxburghia, Smilacina) ; 



IV. Leaves parallel-veined (Figs. 51, 60); rarely net- 

 veined, and even then with strong parallel ribs (Dioscorea, 

 Fig. 89 ; Smilax, Fig. 241) ; 



V. Growth endogenous (Fig. 61) ; stem usually simple 

 (Palm). 



91. Specialization. 



— Plants growing in 



still, fresh water best 



preserve the features 



of ancient types, be- 

 cause they have fewer 



dangers than land 



plantSjin theway of in- Fig. 61. — Transverse and veitical sections of a solid en- 



trusion from animals, dogenous stem. 



winds, etc. The Plowering-Eushes and Water-Plantains (Figs. 58, 



62) are therefore regarded as 

 the most highly -developed 

 types in Endogens. All their 

 floral parts are in threes or 

 a multiple of three ; and all 

 are distinct (like pai-ts sep- 

 arate) and free (unlike parts 

 separate). Being fertilized 

 by insects, they have large 

 bright petals to attract such 

 visitors. Looking down the 

 line of development, we see 

 the Lilies (Figs. 56, 63 A). 

 They are insect-fertilized ; 

 but, being land plants, they 

 specially adapt themselves to 

 their dangers. The 3 ova- 

 ries cohere into a 3-celled 

 capsule (Fig. 8, 4), each cell 

 with many seeds ; the 3 styles 

 cohere into one, with a 3-lobed stigma ( Pig. 56). Still lower are the 

 Grasses (Figs. 51, 52, 64). They are wind-fertilized; their stems and 



€.2 



Fio. 62. — Diafcram of Alisma family : 

 d, petals; c, outer whorl of stamens; 

 whorl ; a. ovaries. 



