152 ABRONIA TJMBELLATA. 



are about one half the natural size. "We may add, as an illustration of the doc- 

 trine that ' extremes meet ', that the leaves of both species of Milla yield an 

 alliaceous odour when bruised, so slight is the interval separating the most 

 delicious perfumes from those of an opposite character. 



ABRONIA TJMBELLATA. 



Umbelled Abronia. 

 Linnean Class— Pentandria. Order— Monogynia. Natural Order — Nyctaginaceje. 



The Abronia umbellata offers us an example of a class of plants termed by 

 Botanists monochlamydeous ; in other words, having but one floral envelope, and of 

 which the common Marvel of Peru is a familiar illustration. In the majority of 

 Exogenous plants, the flowers comprise both an outer and inner envelope, termed 

 respectively the calyx and corolla ; but in a certain number of Natural families the 

 latter of these is wanting, or it may be that both are present in a united form. 

 By those who take this view, such a flower is termed a perianth, though it 

 would be more proper to confine that term to the blossoms of Endogenous plants. 



To one of the most curious of these Natural families, the Nyctaginaccee, or 

 Marvel of Peru tribe, our Abronia umbellata belongs ; and although, at first sight, 

 the relationship between the plant which forms the type of that Order and our 

 present subject, will appear but slight, we have only to turn to the enlarged 

 figure of a single blossom given in our sketch, to be struck with its resemblance 

 in miniature to the flower of the plant just named. The most singular feature 

 of the Nyctaginacem is the hardening of the base of the calyx after flowering, 

 by which the seed becomes enclosed in a woody envelope which supplies the 

 place of the usual integuments. Thus, in the fruit of the common Marvel of 

 Peru, the hard external coating is not, as might be supposed by some, a true 

 seed-shell, but the remains of the floral envelope much enlarged, and so indurated 

 as to serve most efficiently the purpose of a covering to the grain. There is 

 however, no adhesion between it and the seed, nor does it completely surround 

 it, a small orifice being visible at the apex. 



The same feature we shall find occurring in the Abronias, though in a modified 

 form, as will be presently explained. Our figure, although representing with 

 considerable accuracy the character of the flower-heads, and the shape of the 



