80 WILLIAM TRELEASE ON THE 



wards with considerable force (PI. 10). The segments of the ovary having ah-cady bent 

 themselves at a sharp angle with the beak, the resnlt of this movement is to throw the 

 seed, or even the entire carpel, to a considerable distance. So far as I have examined 

 them in the field, or as the indications of hcrbarinm specimens are to be trnsted, our spe- 

 cies behave uniformly in this manner (though in L. piisillum the carpels do not bend 

 abruptly above the ovary) with the exception of G. Rohertiamim (PI. 10, fig. 10) and some 

 of the other small-flowered species, where the ripened segments of the ovary, though 

 nominally dehiscent, I'emain closed about the seeds, imprisoning them. To compensate 

 for this, these segments nearly separate from the stylar appendages, with which, in G. 

 Robertianmn, they are finally connected only by a pair of slender silk-like bundles of 

 fibres. "When the style at length breaks away and suddenly becomes arched, these 

 fibres give way and the ovai'ian segment with its enclosed seed is thrown off with much 

 force, often to a distance of many feet. (N^ote 4.) 



ERODIUM, L'Hcr., Geran. PI. 1-6; Benth. and Hook. Gen., i, 272. 



At length mostly caulescent, with often pinnatisect leaves ; peduncles mostly umbel- 

 latcly several-flowered; flowers nearly regular, the upper petals a trifle smallest; stamens 

 with anthers 5, opposite the sepals, alternating with as many sterile filaments; carpels 

 very sharp-pointed below, covered with obliquely ascending appressed hairs, at most tar- 

 dily dehiscent ; styles spirally twisted below when ripe, bearded on the inner side ; seed 

 obconical or oblong, not sculptured; othei'wise as in Geranium. — About fifty sj^ecies, 

 mostly natives of the north temperate portion of the Old World, some of them widely 

 distributed as weeds. 



Synopsis of ^ortii AMEPacAX Species. 



*Leaves round-ovate, with approximated lobes, or not lobed; seed large, 4-5 mm. long. 

 Pedicels glandular, seeds stout. ...... E. macrophyllum. 



Not at all glandular, seeds slender. ...... E. Texanum. 



* * Leaves ovate-oblong, with approximate lobes; seed smaller, not over 3 mm. long. 

 Fruit very small, beak 25 mm. long. . . . . . E. inalachoides. 



Fruit much larger, beak 70-120 mm. long. 



Leaves pinnatifid with irregularly toothed segments. . . . E. Botrys. 



Cauline leaves liipinnatisect Avith linear-oblong segments ; sepals and fruit very 

 large. ........... E. Ciconium. 



* * * Leaves oblong, with remote segments; seed as in the last. 



Leaves pinnatifid, or bipiiinatifid, with irregularly serrate segments; stipules obtuse. 



E. moschatum. 



Leaves bipinnatisect, with narrow shari)-toothed segments; stipules acute. 



E. cicutarium. 



