144 AN INTRODUCTION 



CHAP. XI. 

 OF PLACENTATION. 



BY PLACENTATION* is meant the disposition of 

 the Cotyledons at the time when the seed is begin- 

 ning to grow. Plants in respect to Piacentation, are 

 termed, 



1. ACOTYLEDONES, without cotyledons, when this 

 part is wanting ; as in Mosses. 



2. MOXOCOTYLEDONES, with a single cotyledon')" ; 

 and these are either, 



Perforate ; as in Grasses. 

 Unilateral; as in Pulms; or, 

 Reduced ; as in Cepa. 



3. DICOTYLEDONES, having ^two cotyledons; and 

 these are either, 



Imniutate, unchanged ; as in the class Didynamia ; 

 and in plants, whose pericarpium is a legumen, po- 

 mum or drupa. 



Plicate, folded; as in Gossypium. 



Duplicate, doubled : as in Malva; and in the class 

 Tetracjynamia. 



Obvolute, rolled up; as in Helxine. 



Spiral, turned like a skrew ; as in Salsola, Sa- 

 licornia, Ceratocarpus, Basella, and all oleraceous 

 plants^; or, 



Reduced ; as in umbellate plants. 



* The Cotyledons of the seed in vegetables answer the pur- 

 pose of the Placenta in the animal economy ; and hence the 

 disposition of the Cotyledons is called Placentaiion. 



f Linnaeus observes, that the Monocotyledones are pro- 

 perly Acotyledones; the Cotyledons remaining within the seed. 



{ Pot herbs. The Oleraceous plants make an order in the 

 Fragmenta Method! ^ T aturalis of Linnaeus ; consisting of 



