THE DICOTYLEDONES 1633 



The gynoecium consists of from two to many carpels. The ovary 

 is usually unilocular with a number of placentas equal to that of the carpels, 

 forming a series of radial plates, arising from the ovary wall and almost 

 meeting in the centre. A false septum may be developed in the unilocular 

 ovary to produce a bilocular appearance. The ovules are anatropous or 

 campylotropous. The stigmas are opposite or alternate with the placentas. 



The fruit is a capsule opening either by valves or pores; it is rarely 

 indehiscent. 



The seeds are small, spherical, or ovoid and often minutely warted or 

 reticulate; occasionally they are arillate. The embryo is minute with an 

 oily endosperm. 



The family includes twenty-eight genera with about 600 species, which 

 occur chiefly in northern temperate regions. The chief anatomical features 

 of the family are the absence of subsidiary cells accompanying the stomatal 

 guard cells and also the occurrence of simple perforations in the vessels. 

 The wood parenchyma has simple pits. Secretory canals producing white 

 or yellow latex are widely distributed. The classification of the Papa- 

 veraceae is simple: 



I. Papaveroideae 



The petals are not spurred : the number of stamens is indefinite and the 

 number of carpels varies from two to indefinite. Eschscholtzia, Chelidonium, 

 Glaiicium, Papaver, Meconopsis, Argemone, Platystemon, Bocconia, Macleava. 



II. Hypecoideae 



The petals are not spurred: the stamens are four in number and the 

 gynoecium is composed of two carpels. Hypecoum, Pteridophyllum. 



III. Fumarioideae 



The petals are spurred and there are two branched stamens, each with 

 three members. Dicentra, Corydalis, Fiimaria. 



The section Papaveroideae includes the regular actinomorphic types in 

 which the petals are usually large and conspicuous. Many species exude 

 a milky or yellowish juice. The largest genus is Papaver (Fig. 1493) which 

 contains about no species. They are found in central and southern Europe 

 and in temperate Asia, but Papaver nudicaule, the Iceland Poppy, grows as 

 far as the polar circle in both hemispheres as well as in the mountainous 

 regions of central Asia and in Colorado. Many poppies are annual weeds, 

 but some are perennial. They contain an elaborate laticiferous system often 

 accompanying the phloem. This latex may contain various alkaloids and 

 P. somniferum, the Opium Poppy (Fig. 1494), is largely cultivated in India 

 and the Far East for the opium which is extracted from the latex of the 

 unripe fruits. 



The genus Meconopsis (Fig. 1495) occurs mainly in southern and eastern 

 Asia and is cultivated in this country, particularly M. betonicifolia on account 

 of its bright blue flowers. Other species have yellow flowers. The genus 

 differs from Papaver in the presence of a distinct style, on which the four- or 



