188 ON SEEDLINGS 



CISTINE^E. 



Benth. et Hook. Gen. PI. i. 112. 



The ovary in this Order is free, consisting of three to five 

 carpels united by their edges only, and is one- or partly three- 

 to five-celled by the prominence or inflection of the three to five 

 parietal placentas. The ovules are generally numerous on each 

 placenta, but there are only two in Hudsonia and Lechea; 

 ascending and projecting into the cavity of the ovary on long or 

 rarely short funicles, and orthotropous, rarely semianatropous 

 as in Lechea and Fumana by the funicles being partly adnate 

 to the placenta. Orthotropous ovules are generally associated 

 with one-seeded fruits as in Polygonaceae, many Urticaceae, 

 and Juglandaceae, so that Cistus and Helianthemum are very 

 exceptional in possessing orthotropous ovules in a many-seeded 

 ovary. The fruit is a capsule dehiscing by as many valves as 

 there are carpels. The dehiscence being loculicidal, the seeds 

 are borne along the centre of the valves as in the Violarieae 

 to which the Cistineae are allied. The seeds are numerous in 

 the two leading genera, Cistus and Helianthemum, and are 

 ovoid or variously angled by mutual pressure. They contain 

 a large quantity of a farinaceous or mealy endosperm, some- 

 times occupying one side of the seed only as in Cistus 

 laurifolius, or in some cases almost equally distributed and 

 completely surrounding the embryo. The latter is there- 

 fore generally excentric, and curved, spirally convolute, or 

 conduplicate, rarely nearly straight as in Lechea. The coty- 

 ledons are plano-convex, nearly flat or narrow, and semiterete. 



Cistus laurifolius, which may be taken as typical of the 

 group, has a spirally coiled, excentric, comparatively large 

 embryo, with linear, obtuse, semiterete, incumbent cotyledons 

 lying in the narrow plane of the somewhat flattened seed, with 

 their backs to the placenta. The cotyledons are equal, the 

 inner one in this case at least being more coiled than the outer. 

 The embryo of C. villosus seems to be more central than usual, 

 and the cotyledons are linear-oblong, incumbent, and shorter 

 than the radicle. The embryo of Helianthemum, according to 

 Bentham and Hooker, is uncinate, biplicate, or circumflexed. 



