130 WEEDS OF THE FARM AND GARDEN 



suture is where the leaves meet. The placenta is that part 

 of the ovule where the ovules are borne. An a. vile placenta 

 occurs in a compound pistil where two or more closed 

 carpels cohere; such ovaries are two, three or more 

 celled. A parietal placenta appears in a compound pistil 

 when the ovules are borne on the walls of the ovaries, as 

 in the poppy and Rocky Mountain bee plant. In pinks 

 and purslane, the compound pistil is one-celled with a 

 free placenta. The parts of an ovule are the two coats, an 



Fig. 75- Pollen grains in a stage preceding the formation of a 

 pollen tube. A-F, different stages. (Caldwell-Coulter.) 



outer and an inner, the chalaza at the base where the coats 

 and nucellus blend; the nucellus, is the body of the ovule. 

 The inicrop\'le is the opening" left after the passage of the 

 pollen tube into the ovule. There is usually a stalk called 

 the funiculus on the seed ; the embryo sac contains the 

 egg cell. Ovules may be erect when they arise from the 

 bottom of the cell ; ascending, when extending upward and 

 attached at the side; horizontal, when borne on the side 

 horizontally as in mandrake; suspended, when hanging 

 from the apex ; pendulous, when more or less hanging or 



