THE FLOWER ioi 



believed that the placenta, which is basal, is the apical 

 continuation of the axis or thalamus inside the ovary. 

 Such a placentation is usually included under the head 

 of free-central. In NymphcBa or shalook and Buto- 

 mopsis lanceolata (see fig. 256, sp), a common aquatic 

 marsh plant, ovules are inserted all over the inner 

 wall of the ovary. The placentation in such cases is 

 said to be superficial. In an apocarpous simple 

 pistil, e.g. Pea, or multiple pistil, e.g. akanda and 

 Champa, the placenta lies inside the ventral suture, 

 and is therefore said to be ventral (see fig. 91). 



The Ovule or Macrosporangium. — The ovule 

 arises as a small bud or mass of tissue from the pla- 

 centa. As the bud develops it gradually becomes 

 thick and rounded at its apex and thin at its base, till 

 the thick apical portion, now called the nucellus, is 

 separated from the placenta by a short thin stalk called 

 the FUNiCLE. From the funicular end of the nucellus 

 one or more, usually two, coats or integuments begin 

 to grow and gradually envelop the nucellus, excepting 

 a small portion of it opposite to the funicular end, 

 which is thus left open or free from integuments. 

 This open or uncovered part of the nucellus is known 

 as the MiCROPYLE (small gate). The funicular end of 

 the nucellus from which the coats grow is known as 

 the chalaza. Within the nucellus, close to the micro- 

 pylar end, is developed a single cell, called the em- 

 bryo-sac or MACROSPORE, which encloses within it 

 the oosphere, ovum, or female cell, mentioned before. 

 In rare cases the nucellus remains naked, or without 

 coats. 



Ovules are usually divided into three classes: 

 (i) ORTHO- or a-tropous (straight) — a, in which, as 

 described above, the chalaza lies nearest to the pla- 

 centa, and the micropyle farthest from it; (2) ana- 



