NO. 3 dunkle: plant ecology, channel islands 301 



L. argophyllus ornithopus Ottley. 

 Santa Cruz, Santa Catalina, 

 Santa Barbara, San Nicolas. 

 The Santa Barbara, San Nicolas 

 forms have peduncles approximately 

 one-fourth the length of the peduncles 

 in the Santa Catalina form. 

 Calyx teeth shorter than the tube. 



Stems woody, branches short virgate, leaves more or less imbricated 

 on the branches. 



L. argophyllus adsurgens Dunkle. 

 San Clemente Island. 

 Stems herbaceous, decumbent. 

 Umbels sessile or nearly so. 



L. argophyllus Greene. 

 Pine belt of Southern California Mountains. 

 Umbels short peduncled. 



Umbels approximate at ends of branches, blade of banner sub- 

 equalling claw, silvery canescent. 



L. argophyllus argenteus Dunkle. 

 San Clemente Island. 

 Umbels scattered along branches, blade exceeding claw. Leaflets 

 5, broadly elliptical, satiny canescent. 

 L. argophyllus decorus Ottley. 

 San Gabriel, San Bernardino, and 

 San Jacinto mountains. 

 Leaflets 5-7, narrowly-elliptical, silky canescent. 

 L. argophyllus Hancockit Dunkle. 

 San Clemente Island. 

 This species well illustrates how various genetic tendencies have 

 been interwoven into an intricate pattern. The island varieties of Erio- 

 gonum latifolium and of Platystemon californicus show similar ten- 

 dencies. 



Other endemics which illustrate the effect of the environmental 

 influences are those which have developed a higher degree of pubescence 

 on the foliage than is to be found in related mainland species or varie- 

 ties. This, according to Lundegardh, is the effect of a relatively high 

 alkaline content of the soil (Lundegardh, 1931), but here the wind is 

 probably at least an equally potent cause of pubescence. Examples of this 

 type of development include : 



