342 SYSTEMATIC BOTANY. 



usual presence of perisperm in the seeds, and in the flowers not being 

 arranged in catkins. There is a further relation to the Chenopodiaceae, 

 which, however, besides the circumstance that they are only occasionally 

 diclinous, have the embryo curved round the outside of the perisperm. 

 The pollen is generally "spherical. The leaves abound in clusters of 

 crystals contained in large cells (cystoliths). The leaves of Nettles are 

 often oblique, the smaller lobe of the base of the leaf being directed 

 towards the branch from which it springs, contrary to what generally 

 happens in oblique leaves. 



Distribution. The UrticecB are generally diffused, but are much more 

 abundant in the intertropical regions than elsewhere. 



Qualities and Uses. Edible fruits and valuable fibres are the principal 



Sroducts of this Order. Bcehmeria (Urtica} nivea furnishes the iibre for 

 hinese " Grass-cloth," Rhea or Ramee ; B. Puya yields another valuable 

 fibre ; and the fibre of the Stinging-Nettle ( Urtica dioica) was formerly 

 used ; U. tenacissima furnishes cordage in Sumatra. The juice of some 

 Nettles is extremely irritant. 



CANNABINACE^: constitute a small group often in- 

 cluded under Urticacese, but differing in their stamens Fig. 431. 

 not being elastic, their elongated, not rounded, anthers, 

 and in their curved aperispermic embryo (fig. 431). 

 By Baillon they are placed with the Elms. Cannabis 

 sativa furnishes the hemp of commerce, which consists 

 of the woody fibres of the plant separated by maceration. 

 C. indica yields a narcotic resinous product known as 

 Indian hemp. Humulus Lupulus, the Hop, is well known Seed oiHu 

 for its aromatic bitter properties. 



ARTOCARPACE^E are trees or shrubs, or rarely herbs, with milky 

 juice ; alternate leaves, usually provided with convolute deciduous sti- 

 pules ; diclinous flowers, males in catkins, females in heads or flat recep- 

 tacles ; perianth 3-4-parted or none ; stamens not elastic ; ovary 1 -celled ; 

 ovule solitary ; perisperm fleshy or none ; embryo straight or curved ; 

 radicle superior. 



The Order is divided into two tribes : 1. ARTOCARPE^:, with stamens 

 inflexed in the bud, e. g. Artocarpus. 2. MOBE^:, with straight fila- 

 ments, e. g. Morus, Ficus. 



Affinities, &c. The main difference between this group and the Urtica- 

 cesd lies in the milky juice and general habit. By Baillon it is classed 

 under Illmaceee (see that family). The inflorescence and fruit of these 

 plants are curious : in Dorstenia the flowers are embedded in the top of a 

 tabular fleshy peduncle (fi^. 148) ; in Ficus enclosed in an excavated 

 fleshy peduncle (fig. 147) ; in Moms the female flowers are developed in 

 a sort of capitulum, and subsequently coalesce into a compound fleshy 

 fruit, resembling a blackberry (fig. 307), but each " pip " is formed from 

 a distinct ovary ; in Artocarpus the numerous flowers are crowded on a 

 globular fleshy peduncle, which enlarges into a large fleshy fruit, some- 

 times weighing 30 Ibs. Ficus indica (the Banyan tree) and some other 



