406 GERANIACEAE 



2. ERODIUM Ij'IIer. Storksbill 



Annual herbs. Leaves opposite, often unequal, either simple or pinnate, Avith 

 one interpetiolar stipule on one side and two on the other. In vegetative characters 

 verj'' similar to Geranium ; the flower and fruit nearly the same, but tlie stamens 

 with anthers 5 only, the alternate filaments sterile and scale-like. Styles bearded 

 inside. Pedicels after anthesis commonly retrocurved. — Species 60, all continents 

 but chiefly in the Mediterranean region. (Greek erodios, a heron.) 



Alien Erodium immigrants. — The first species of this genus entering California as an immi- 

 grant from the Old World was Erodium cicutarium L'Her. It is almost undoubted that it came 

 with the earliest European settlements, that is, from Spain by way of Mexico. By 1844 it was 

 abundant in the Great Valley (Fremont, Rep. Expl. Exped. to Ore. and n. Cal. 243, 253), and by 

 the early days of the American occupation of the state it was widely diffused through all the 

 open lowland country. It occurs not only in the fields and open hills of coastal Southern Cali- 

 fornia, the Coast Ranges, Sierra Nevada foothills and Great Valley, but it has adapted itself to 

 the most arid parts of the Mohave Desert where it is found everj^vhere on flats, uplands and 

 mesas. Probably no other species is represented in the Mohave Desert at the present time by 

 so large a number of individuals as Erodium cicutarium. In the desert (as elsewhere) its seed 

 germinates readily under slight rainfalls; it develops promptly a deep-seated taproot; and 

 under unfavorable conditions for growth, plants which do not rise above one-half to one inch in 

 stature may flower and produce seed. A severe habitat of another kind, geographically distant, 

 is represented by the moist sea-beaches of Mendocino County, where on account of adverse 

 temperature and soil conditions the prostrate plants are seldom above two to three inches in 

 diameter. But everywhere in the intermediate habitats, the low open foothills and semi-arid 

 valleys, the plant is much at home and often forms 25 to 40 per cent of the ground cover. Highly 

 esteemed as a forage plant it is one of comparatively few unbidden aliens that represent an 

 economic asset and not a disadvantage as a pest or weed. Its wide distribution is undoubtedly 

 associated with the nature of its preferred habitat, the open grasslands, and the flocks of sheep 

 which from the earliest days of Spanish-California have grazed them. 



Erodium moschatum L'Her. was the second species to appear. It may have come in with 

 E, cicutarium at the founding of the Spanish missions, but of the two, the latter became by far 

 the more widely distributed. Keeping mainly to the coastal valleys, Erodium moschatum is on 

 the whole rather restricted in habitat. It is chiefly a plant of cultivated ground and is abundant 

 only in rich lands of valley orchards, vineyards and gardens, where it is commonly the sole 

 species of this genus. Often growing very rankly in good soils we have recorded occasional 

 plants with stems 5 to 6 feet long and leaves 14 to 15 inches long. On account of its musky 

 foliage it is less valued as stock feed than the Red-stem Filaree. 



It was nearly a century later that Erodium botrys Bertol. appeared in California. "We first 

 noticed it in Vaca Valley in 1885, though one station had been recorded previously in the Botany 

 of the California Geological Survey (1:95, — 1876). Since that time it has spread steadily and 

 persistently and seems to displace Erodium cicutarium as it advances. Its rosettes of leaves are 

 formed in winter or early spring, lie flat on the ground and protect the plant from too close 

 competition. Biologically it possesses a more effective rosette than E. cicutarium, because 

 shading the ground more completely. Its aggressive behavior has been studied by us at many 

 places in the Sierra Nevada foothills and indicates wide-spread and successful occupation of the 

 open gravelly and clay plains and lower hills where it has displaced Erodium cicutarium. About 

 Table Mountain in Fresno Co. it formed in 1929 from 20 to 60 per cent of the ground cover on 

 most of the pastured hills. In the region of lone, the same year, on the low rolling plains it 

 formed over vast areas 50 to 90 per cent of the cover (Jepson Field Book 49:119, ms.). In 

 1927 similar observations were made in the foothills of the upper Sacramento Valley. On the 

 low rolling plains of western Tehama Co., E. cicutarium was in 1899 the only observed species 

 (Jepson Field Book 1:146, ms.). In 1929, on the contrary, E. botrys was often the dominant 

 in that upper valley region. All this illustrates well the march of an immigrant, the conquest 

 of the grassy foothills by alien populations from the region of the Mediterranean. 



Sepals not bristle-tipped ; leaf -blades mostly cordate or subcordate at base. 



Leaf -blades round-ovate to oblong-ovate, sub-palmately cleft or parted 1. E. texanum. 



Leaf -blades cordate-reniform, crenately toothed or shallowly lobed 2. E. macrophyllum. 



Sepals bristle-tipped or setose-tipped; leaf -blades oblong or oblong-ovate, not cordate at base, 

 pinnatifid or pinnately divided into toothed or cleft lobes. 

 Leaf -blades oblong-ovate, pinnately cleft into broad crenate lobes; beak of fruit 2^ to 5 



inches long; sepals bristle-tipped; glands of the flowers greenish 3. E. botrys. 



Leaves pinnate; beak of fruit 1 to 1% inches long; glands of the flowers reddish or brownish. 

 Leaflets serrate or merely incised; petals with naked claws; sepals without bristles or 



sometimes tipped with 1 or 2 short setose hairs; stipules large, obtuse 



4. E. moschatum. 



Leaflets pinnatifid ; petals with ciliate claws ; sepals tipped with 1 or 2 long bristle-like 



hairs; stipules commonly small and acute 5. E. cicutarium. 



