SECT. II PHANEROGAMIA 545 



Choripetalae and contrasted as Monochlamydme with the Dialypetalae, 

 which have a perianth of two whorls (of. p. 526). 



Series I. Choripetalae 



A. MONOCHLAMYDEAE 



Order 1. Veptieillatae 



Single Family, Casuarinaccae (--). Highly branched trees, inhabiting the sea- 

 shore and mountains of Australia and South-East Asia. Young shoots with an 

 E(]uisetum-\\ke. habit. Anemophilous. ISIale flowers in whorls ; each has a single 

 stamen and a perianth of two leaves. Female flowers chalazogamic (cf. p. 512) ; in 

 lateral inflorescences ; ovary of two carpels ; no perianth. Winged indehiscent 

 fruits enclosed by the lignified bracteoles. 



The following orders 2-5 agree in the unisexuality and anemophily 

 of their very simple flowers. They include various transitional forms 

 from chalazogamy to porogamy. 



Order 2. Jugrlandiflorae 



Aromatic Avoody plants, with anemophilous, unisexual flowers in 

 catkinate spikes, sometimes containing very few flowers. Ovary bi- 

 carpellary and unilocular Avith a single, basal, erect, atropous ovule. 

 Fruit, a drupe. Seed without endosperm. 



Family 1. Juglandaeeae C--^). — Conspicuous, monoecious trees of 

 the northern hemisphere with imparipinnate, aromatic leaves arranged 

 alternately. Stipules wanting. Male catkins springing from the 

 leaf-axils of tAvigs of the preceding year ; female floAvers in terminal 

 spikes containing more or less numerous flowers. Ovary inferior. 



The Walnut, Jiiglans regia (Fig. 516), is the best-known representative of the 

 family. It is endemic in Western Asia and the eastern portion of the Mediter- 

 ranean region, but the tree is in cultivation throughout Europe. In spring the 

 axillary buds of the previous season produce long, thick, pendulous catkins bearing 

 numerous flowers. Each of the latter has 3 to 5 perianth segments, and these together 

 with the two bracteoles are adherent to the bract and surround the numerous 

 stamens, which face towards the tip of the inflorescence. The female flowers in 

 smaller numbers are borne at the summit of the young shoots. The two carpels 

 terminate in large, feathery, diverging stigmas. The perigone is adherent to the 

 bract and bracteoles and reaches to the summit of the inferior ovary. The single 

 loculus encloses an atropus, basal ovule. Fruit, a drupe. The exocarp contains 

 abundant tannin. The hard eudocarp is divided into two valves in the plane 

 of the dorsal sutures of the coherent carpels, the limits of which are indicated 

 by the partial septum at the lower part of the fruit. Within the stone is the 

 embryo, enclosed in a thin seed-coat. The lai'ge cotyledons, which contain oil 



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