580 



PAET III. — THE CLASSIFICATION OF PLANTS. 



The OTarj is either superior or inferior, di- or tri-merous, with few 

 ovules. The fruit (with the exception of Order 7, the Salicaceae) 

 becomes by abortion one-seeded, and is indehiscent : the seed has 

 no endosperm. The flowers are furnished with bracts which often 

 form investments for the fruit : their arrangement in most of the 

 orders is as follows ; in the axil of a scaly bract (the bracts being 

 arranged spirally in the amentum) is a flower (&) with two 

 bracteoles a and (B, in the axil of each of which is another flower 

 with two more bracteoles a' and p (Fig. 382). The plants are 

 trees and shrubs. 



Order 1. Betulacej:. The flowers are monoecious, but in dif- 

 ferent catkins. The ? flowers have no perianth : the ovary is 

 bilocular, with two ovules : the fruit is one-seeded, indehiscent, 



(: 



Jl 13 





Fig. 382.— Typical diagram of 

 a group of flowers in the Amen- 

 tales : d bract ; h the median 

 flower with its bracteoles, a and 

 /3 ; b'b" the two lateral flowers, 

 with their bracteoles a' and j3'. 



Fig. 383.—^ Scale from a <J catkin of 

 Alnus incana: the axillary branch adheres 

 to the scale (s), it bears four bracteoles and 

 three flowers : two of the flowers are seen 

 laterally (b' h'), the median one from above ; 

 p perianth ; a stamens. B Bract (s) of a ? 

 catkin of the same plant : its axillary branch 

 bears two lateral branches, each of which 

 bears two bracteoles (u v) and one flower ; / 

 the ovary; n the stigmata (magnified and 

 diagrammatic). 



without any investment : the bract is coherent with the two or four 

 bracteoles (the bracteoles a' are always absent) to form a three- 

 or five-lobed scale, which does not adhere to the fruit. 



Alnus, the Alder. In the <J amenta three flowers with four bracteoles 

 (a, /3, /3', ^') occur in the axil of the bract, each flower having a perianth of 

 four segments, and four unbrancbed stamens. In the ? amenta the median 

 flower is absent ; the four bracteoles coalesce with the primary bract (Fig. 383 B, 

 V «) to form a five-lobed woody scale which persists after the fall of the fruit 

 ■which is not winged. The $ catkins are borne terminally, and the ? laterally 

 on the highest lateral branch, on tl e shoots of the previous year; they are not 

 enclosed by bud-scales during the winter, and blossoming takes place before 

 the unfolding of the leaves. The leaves have usually a J arrangement : in 

 A. incana^ the White Alder, the leaves are acumii ate and gray on the under 



