358 



OVULES 



bent down against its stalk (funicle,/.), so that the micropyle (m.) 

 is directed towards the placenta. The greater part of the funicle 

 is in this case fused with the adjacent portion of the outer in- 

 tegument, which is in consequence not easily distinguished on 

 this side. The fused region, known as the raphe (r.), is traversed 

 by the vascular bundle (V.b.) which enters the funicle from the 

 placenta, and which extends as far as the base of the nucellus 

 (a region known as the chalaza, Ch.). 



FIG. 207. Ovules and stages in their development (after Le Maout and 

 Decaisne). A, Young ovule, before the integuments appear, showing 

 nucellus (Nu.) and dividing archesporium (ar.). B, Orthotropous ovule 

 of Polygonum. C, Anatropous ovule in longitudinal section, showing 

 funicle (/.) and raphe (r.). D, I-IV (in the direction of the arrow), 

 successive stages in the development of the anatropous ovule of 

 Chelidonium. E, Successive stages (in the direction of the arrow) in 

 the development of the campylotropous ovule of the Mallow (Malva). 

 i., inner integument ; n., nucellus ; o., outer integument. 



Erect or orthotropous ovules, in which the micropyle faces 

 away from the placenta, and lies at the opposite end to the 

 usually short funicle (Fig. 207, B), are much less frequent, but 

 are found, for example, in the Knot weeds (Polygonum}. Another 

 rare type, the campylotropous ovule (Fig. 207, E), seen in many 

 Caryophyllaceae, is bent in such a way that the stalk appears 

 to be attached midway between the chalaza and micropyle. 



