CHAPTER XVI. 



WEEDS. 



The great extent of foreign plant immigration is perhaps sufficiently 

 emphasized in the Reader. To begin at once, then, with the individual 

 weeds : The malva, bur-clover, and filaree have already been much 

 considered in the Reader. The fox-tail grass, Hordeum murinum, 

 Linn., is surely familiar to all Californians. Both its awns, and its 

 inner floral envelopes, which are sharp pointed at the base, are pro- 

 vided with bristles, rendering the plant an almost universal pest. 

 Prof. Hilgard of the State University, in his report for the year 1890, 

 is my authority for the statement that the soft brome grass, Bromus 

 mollis, Linn., is likely to aid in the extirpation of the fox-tail grass; 

 this brome grass is not yet abundant in the south. The wild oat, 

 Avenafatua, Linn., is valued for hay, although its awns sometimes 

 do mischief to cattle and horses. An extremely pretty foreign grass, 

 Achyrodes (Lamarckia) aureum, O. Ktze., with fluffy, plume-like 

 spikes of minute flowers, is becoming very common in the south. It 

 seems unfair to include this pretty grass among weeds, but it prob- 

 ably has little value for pasturage, and it is well provided with means 

 of dispersal. It is doubtless true that the Bermuda grass will never 

 be troublesome on land not irrigated, but it ruins many a lawn. The 

 chess, though frequently imported with grain seed, does not succeed 

 in California, but the darnel, a species of Lolium, is troublesome in 

 some parts of the state. The alkali grass, Distichlis maritima, Raf., 

 is not easily exterminated from moist alkali soil. 



The extermination of black mustard, probably introduced as a con- 

 diment, is the most serious weed problem of the south. Such is the 

 vitality of its multitudinous seeds, that mowing the flower stalks for 

 a single season seems to have but little permanent effect. The seeds 

 are utilized commercially to some extent. The radish, Raphanus 

 sativus y Linn., is a rather common weed, but is not generally per- 

 sistent. 



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