162 



examined the region. I hardly believe this is the correct explan- 

 ation since the last ten years of collecting in these mountains 

 have added but two species which were not collected on the first 

 few trips. Moreover, it is not hard to find ferns in the Organs 

 at any time of the year, while in the other mountains mentioned, 

 aside from patches of the bracken, ferns are relatively rare. 

 Extended collecting in the Organs has served to show how 

 widely distributed some of the ferns have become : almost every- 

 where one goes in the range he may find one or more kinds of 

 the ferns peculiar to the arid region. 



As would naturally be expected from the climatic conditions 

 afforded by the range, the ferns almost all belong to the group 

 assigned by Dr. Underwood * to the Sonoran province. Of the 

 thirty-six species referred to this province by him, fifteen are to 

 be found in the Organs and several of them are quite abundant. 

 To a collector who thinks of a plant like the lady-fern or the 

 maidenhair when a fern is mentioned, these mountains with their 

 peculiar fern-flora would indeed be a revelation. The preservation 

 of the small amount of moisture annually received is of the utmost 

 importance in the economy of these plants, and the devices used to 

 obtain this end are exceedingly interesting : the rolling up of the 

 pinnules and exposing a hairy, scaly, or mealy surface to the 

 action of the atmosphere. Drying up does not hurt them, and 

 they are ready to grow at any time of the year when the water 

 falls and the temperature is above the freezing point. 

 The following is a list of the species, with notes : 

 Bommeria hispida (Mett.) Underw. Commonly forming mats 

 over the warmer rocks with Selaginella rapinicola Underw. 

 Sonoran. 

 Notholaena sinuata (Sw.) Kaulf. One of the commonest spe- 

 cies. On both calcareous and silicious rocks, in dry, warm 

 situations. Fronds i 2 to 16 inches long. Sonoran. 

 N. sinuata integerrima Hook. Collected thus far only on a 

 limestone outlier of the range. Often associated with the 

 species from which it is perfectly distinct in this region. I 

 have never collected any intcrgrading forms, but Dr. Under- 

 *Our Native Ferns and their Allies, 65. 1893. [Ed. 4.] 



