Fig. 344. Orthotropous ovule of Buckwheat: c, hilum and chalaza; f, orifice.
Fig. 345. Campylotropous ovule of a Chickweed: c, hilum and chalaza; f, orifice.
Fig. 346. Amphitropous ovule of Mallow: f, orifice; h, hilum; r, rhaphe; c, chalaza.
Fig. 347. Anatropous ovule of a Violet, the parts lettered as in the last.
[321.] The Kinds of Ovules. The ovules in their growth develop in three or four different ways and thereby are distinguished into
Orthotropous or Straight, those which develop without curving or turning, as in Fig. [344]. The chalaza is at the insertion or base, the foramen or orifice is at the apex. This is the simplest, but the least common kind of ovule.
Campylotropous or Incurved, in which, by the greater growth of one side, the ovule curves into a kidney-shaped outline, so bringing the orifice down close to the base or chalaza; as in Fig. [345].
Amphitropous or Half Inverted, Fig. [346]. Here the forming ovule, instead of curving perceptibly, keeps its axis nearly straight, and, as it grows, turns round upon its base so far as to become transverse to its funiculus, and adnate to its upper part for some distance. Therefore in this case the attachment of the funiculus or stalk is about the middle, the chalaza is at one end, the orifice at the other.