30 



DICOTYLEDONS 



This large order is divided into three families: 



A. The Peaflower Family {Papilionacece). 



B. The Cassia Family (Ccesaljnniece) . 



C. The Mimosa Family (Miniosece). 



A. THE PEAFLOWER FAMILY {PapiUonacecB), 

 The Horse Gram Plant [DoUc/ios biflonis). 



(Plate 650.) 

 (Kan. Huruli, Mai. Kollu. Tam. Kollu. San. Khalakula.) 



1. Seed and Germination. — The brown leathery coat of the 

 kidney-shaped seed of Horse Gram is called the testa. On its 

 concave edge there is a large scar with a tiny pit at one end. 

 Soak the seed in water for a few hours, wipe the water oif and 

 squeeze it gently: a little water oozes out from that tiny hole. 

 The scar is called hilum and is the place of the attachment of 



the seed to the pod by 



means of a small cord 

 / W"'^ '"! \ called funicle. The 

 ( & V _H ... i] 1 testa can now be easily 



stripped off from the 



soaked seed and, if care 



be taken to notice the 



relative position of its 

 outer markings and the inside structures of 

 the seed, it will be found that the pointed 

 end of a small stem is directed towards the tiny hole which is 

 termed micropyle. The little stemlet, called liypocotyl, bears at 

 its other end two thick lateral growths, the seed-leaves or cotyle- 

 dons, and between them a tiny bud {])hmmle) of two folded, veined 

 leaves. The seed, then, contains under its coat the future plant 

 in miniature, the embryo, consisting of the hypocotyl, two cotyle- 

 dons and the plumule. 



To observe the first stages of the growth of the plant, we 

 allow the seeds to lie steeped in water for a longer time, say 

 twenty-four hours. If we now examine them, we find the testa 



Fiff. 27. — Bean seed. 



Fig. 28. — Seed of the 



Bean. 

 a. Hypocotyl. b. Seed- 

 leaves, c. Plumule. 



