IG. UNITED STATES AND MEXICAN EOUNDAEY. 



liabitah C( 



he dwelt on by otliers, or may be 



letr to inference from what has been already noted. 



BOTANICAL FEATURES. 



examm 



them 



indicated^ as these furnish ns plain lines of demarcation for separate botanical districts. Thus, 



immediate 



more or less closely to the base of the mountains 



S'^ 



- f 



order, is what may be termed the Lower Mountain Region^ with a still different vege 

 lastly, the Proper 3Ioimtain Region^ producing plants peculiar to elevated localities. 



LITTORAL PLANTS. 



Among the exclusively littoral plants, some are common to the seacoast of nearly all 

 countries ; and these, such as the common Salicorma^ are found here, and it is our intention to 

 notice only those which are peculiar to this particular coast. We mention, first of all, two 

 species of Abronia^ {A. arenaria and A. umbellata^) which spread their trailing branches over 

 the sand dunes which edge the sea-shore^ and with their abundant foliage and beautiful 

 umbelled flowers, erive relief to the barren features of the laudscarjo. 



stems 



Growing with the Abromas a species of ice-plant (3Iesemhrya7ilhemum) is frequently found. 



and triangular leaves. Its showy, though evanescent, pink 

 flowers appear only in bright sun-light, and are succeeded by an edible, juicy fruit. In the 

 same region, though less clogely confined to the sea -beach, is another species of this genus, 



M. 



Here 



may 



senting a thick bed of showy flowers. The leaves and stems are beset with shining glandular 

 little warts, which contain a strongly saline fluid. The flowers, which are ephemeral and very 



iccession from June to August. After the flowering period the 



4 



plant withers and dries up, leaving a thick mat of seed vessels^ 

 commencement of the rainy season ; the hygrometric tissue of the capsule then expands, under 

 the influence of moisture, and the enclosed seeds escape and commence germinating. The dry 

 remains of the plant are frequently burned for the sake of the ashes, which, being strongly 

 alkaline, are used in making soap. Both the species here mentioned are so characteristic of the 

 places they occupy that they would seem to be indigenous, but it is generally thought by 

 botanists that they are introduced. 



Among other plants characteristic of this region are (EnotJiera viridescens^ (Hook.,) Franseria 

 hipinnaiifida ^ and a species of Statice^ which grows near the head of San Diego bay, and seems 

 hardly distinct from S. Limonium. 



The common Salicornia here acquires a shrubby growth, and is frequently entwined with a 



Dodder 



Calif ornica, Franhenia grandifoU 



Layia camosa^ Aromia tenuifolia^ and T% 



Among 



