ALFILAKIA IN ARIZONA. 207 



From these original scattered patches of the plant, some of 

 which iiiav have heen due, also, to the feeding of freighting 

 teams along the way, allilaria was spread bv the ever-increasing 

 herds, at first to tlie adjacent districts and later to tlie more re- 

 mote parts of the territory. 



The rapidity with which it has become more or less domi- 

 nant (i\'er considerable areas in Arizona and other southwestern 

 parts, in couipetirioii with the less and)itious native annual spe- 

 cies, indicates that it is remarkably well adapted to our environ- 

 ment. Its seeds germinate at almost any time during the cooler 

 months of the year, at which })crio(l ou account of the greatly les- 

 sened evaporation, moisture conditions are most nearly uniform. 

 The young plants soon dcA'elop into close, many-leaved rosettes at 

 the centers of which Howcr buds appear as early as January. In 

 virtue of this winter rosette growth alfllaria })l;nits are able to 

 bloom by the time the seeds of many of the shjwer growing 

 species are beginning to sj^rout. Thus our mild winter tempera- 

 ture, combined with winter and early spring rainfall, are factors 

 entirely essential to the successful growth of alhlaria. In all 

 the above desirable qualities alhlaria is similar to the indigenous 

 winter annual species for wdiich this flora is noted. 



Its larger rosettes, however, develop a deeper and more 

 extensive root system than that of the native jdants; also, its 

 hairy seeds, which are provided with curved, sharp pointed bases, 

 are admirably fitted to stick to the coats of such animals as 

 sheep, to whose agency it owes much of its present distribution ; 

 and lastly, a good percentage of its seeds literally plant them- 

 selves even in such unfavorable situations as worn roadbeds, 

 Avashes. etc. All these are important characters for a ])lant grow- 

 ing in this region to possess. 



The matter of self-planting is accomplished by the spirally 

 twdsted awns of the seeds which are hygroscopic, thus rolling 

 and unrolling wdth the changes of moisture in the air from day 

 to day. Small objects, as stems of the floral covering or even 

 masses of the seeds themselves, may act as fnlcrnms against 



