SUPPLEMENT 



The yellow melilot, Melilotus Indica^ All., with fragrant clover-like 

 leaves, and slender spikes of minute yellow flowers, is very common 

 in the south, but it does not infest grain fields as in the north. 

 Melilotus alba, Lam, , the very fragrant melilot with white flowers, is 

 not yet common. The water cress, Nasturtium officinale, R. Br., is 

 not an unmixed evil. The course of introduced weeds is usually, 

 like the star of empire, westward ; but the pond weed, Elodia Cana- 

 densis, referred to in the Reader, is a notable exception. The chili- 

 cothe, already noted in Chapter V, is very troublesome to fruit 

 growers in Antelope Valley and other reclaimed regions of scanty 

 moisture. A near relative of the chilicothe, Cucurbita faetidissiuia, 

 H B K., known as mock orange, Chili-cojote, or calabazilla, fre- 

 quently spreads itself over waste ground and neglected fields in the 

 south, and very troublesome it is if it gains a foothold in cultivated 

 land. It has an underground part of enormous extent, and its stems 

 with their ill scented foliage trail off five OP six feet in every direction; 

 its yellow, gourd-like fruits are exceedingly numerous, and the seeds 

 are well protected by the hard rind of the gourd. 



Poison oak persists for some time in newly cleared land, new shoots 

 springing up from fragments of its sturdy rootstocks. For the same 

 reason, bracken is difficult to eradicate from its former habitat, and 

 several years are necessary to free moist alkali soil from such plants 

 as the yerba mansa (Chapter XIV), wild heliotrope (Chapter IX), 

 wild celery and other swamp-loving Umbelliferae. It is natural that 

 plants with underground parts that enable them to stand repeated 

 croppings, should survive in pasture lands that are little cultivated. 

 The sanicles and other Umbelliferae mentioned in the Supplement to 

 Chapter XII, are examples of this, also the pretty blue-eyed grass, 

 Sisyrinchium bellum, Fig. 61. The numerous little corms given off 

 each season by Brodicea capitata (Chapter VII) render it quite 

 persistent, though not troublesome, in grain fields. In sandy soils 

 Lupinus formosus develops very long roots that are difficult 

 to exterminate. The potency of the morning-glory as a weed also 

 resides in its underground part, and in this case the outcome of 

 the struggle between the weed and the agriculturists is by no means 

 certain. In the south it is the foreign morning-glory, Convolvulus 

 arvensis, Linn., that sometimes drives the farmer from the field, but 

 Prof. Hilgard states that in the bay region it is the native C. Calif or- 

 nicus that remains in possession of abandoned orchards. The pre- 

 eminence of Amsinckia and Eschscholtzia among native weeds is 

 certainly due to their ability to erdure drought, and it is in the 

 regions where rainfall is particularly uncertain that these two weeds 



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