418 



DICOTYLEDONES. 



Linum (Flax) has 5-merous flowers. The main axis terminates in 

 a flower ; and the succeeding branching is cymose, or unipared scorpioid 

 branching by unilateral development, and the flowers in consequence of the 

 vigorous sympodial development of the lateral axis (and also by the leaves 

 being displaced and pushed aside) , assume a position apparently lateral (i.e. 

 racemose) without bracts ; each branch of the sympodium generally has 2 

 leaves. The testa is shining and smooth when dry, but its external cellular 

 layer becomes mucilaginous in water. Radiola has a 4-merous flower. 

 It is a small herb with opposite leaves, and regular, dichasial 

 branching. 



The anthers and stigmas in L. catharticum and iisitatinsinnun develop 

 simultaneously, and cross-pollination as well as self-pollination takes place. 

 L. grandiflorum, perenne, and others, are dimorphic (short- and long-styled). 

 There are 5 nectaries outside the stamens. 



130 species ; Linum and Radiola are native genera. L. usitatissimum is exten- 

 sively cultivated in Europe (especially in Russia and Belgium), N. America and 

 elsewhere (its home no doubt being Asia), partly on account of the oil (linseed 

 oil) which is extracted from the seeds, and partly on account of the bast of the 

 stem, which has very thick-walled cells. The seeds and oil are OFFICINAL. The 

 species cultivated in ancient times was L. anrjiistifolium. Several species are 

 cultivated as ornamental plants. 



Order 3. Geraniaceae. The majority are herbs with dichasial 

 branching, and scattered or opposite, stalked, palminerced (rarely 

 penninerved) leaves with small stipules. The flowers are regular 

 (except Pelargonium) and 5-merous, with 10 or 5 stamens, which 

 are slightly united at the base. Nectaries alternate with the 

 corolla-stamens. The ovary is most frequently 5-locular, deeply 

 5-grooved, and bears 1 well developed style (" beak "), which towards 

 the apex divides into 5 branches bearing stigmas ; ovules 1 in each 

 loculus, pendulous or ascending. The 5 carpels become detached 

 from one another when ripe, and bend or roll back (Fig. 434) or 

 become spirally tivisted in the upper " beak-like " part (Figs. 

 435, 436), whilst a central column (septal column) pei'sists ; each 

 carpel, in consequence, remains either closed, and the fruit is a 

 5-merous schizocarp whose nut-like lower portion, containing the 

 seed, is forced into the ground, thus burying the seed by the 

 movements of the spirally-twisted, hygroscopic '' beak " (Figs. 

 435, 436) ; or it opens along the ventral suture, so that the seeds 

 may fall out, and it is then a 5-valved capsule, with septicidal de- 

 hiscence (Fig. 434) and the rolling up often takes place so suddenly 

 and violently that the seeds are shot out to considerable distances. 

 The embryo is usually green and curved, and the cotyledons are 

 folded ; endosperm is wanting. 



