344 SYSTEMATIC BOTANY. 



ULMAOE^E (THE ELM ORDER) consists of trees with watery juice, 

 alternate stipulate leaves, perfect or 



monoeciously polygamous flowers ; peri- Fig. 432. Fig. 433. 



anth free, membranous, campanulate or 

 irregular (fig. 432) ; stamens definite ; 

 filaments straight or moderately incurved 

 in the bud ; ovary free, 1-2-celled; styles 

 or stigmas 2 ; fruit a single samara 

 (fig. 433) or a drupe ; seed suspended, 

 with little or no perisperm ; radicle 

 superior. Illustrative Genera : Tribe 



1. OELTEJE. Ovary 1 -celled. Celtis, 

 Tournef. ; Mertensia, H. B. K. Tribe 



2. ULME^;. Ovary 2-celled. Planera^ Fig. 432. Flower of uimus. 



Gmel. ; UlmUS, L. ** 433. Fruit of Ulmu*. 



Affinities, &c. These plants, chiefly natives of northern countries, are 

 very closely related to the Artocarpaceae and Urticaceee, and are scarcely 

 distinguished by any general character except the polygamous structure of 

 the flowers. The pollen is ellipsoid with five pores (Mohl). They are 

 timber-trees with bitter astringent bark ; Ulmus campestris is the common 

 Elm-tree, U. montana the Scotch or Wych Elm. Celtis australis, called 

 the Nettle-tree, has a drupaceous fruit of astringent quality. 



PLATANACE^E (THE PLANE ORDER) consists of trees with watery 

 juice, alternate palmately lobed leaves, sheathing stipules, and monoecious 

 flowers in separate and naked globular heads, destitute of calyx and co- 

 rolla, or surrounded by scales or bristles ; the fruits consisting of heads 

 of clavate 1-seeded nucules furnished with a bristly down along the base ; 

 seeds solitary, rarely 2, pendulous ; embryo in very thin perisperm ; radicle 

 inferior. The Plane-trees (Platanus, L.), natives of North America and 

 the Levant, naturalized in our parks and squares, are chiefly remarkable 

 for the beauty of their form and foliage. The stipules are intra-axillary 

 and sheathing, the petioles dilated at the base and concealing the bud, 

 owing to the fusion of the edges over the bud. The structure of the 

 inflorescence is amentaceous as regards arrangement and the absence of 

 envelopes ; but the ovaries are like those of Artocarpece, from which they 

 are divided chiefly by the achlamydeous flowers, the inferior radicle, and 

 the presence of perisperm in the seed. 



MYRICACEJE constitute a small Order of shrubs with resinous-dotted, 

 often fragrant leaves ; monoecious or dioecious achlamydeous flowers, both 

 kinds in short scaly catkins ; stamens 2-16 ; ovary 1-celled, with 1 erect 

 ovule ; fruit drupaceous ; embryo without perisperm ; radicle superior. 

 They differ from the other amentiferous Orders in the simple and free 

 ovary ; they are also related to Urticacese, but differ in the amentaceous 

 inflorescence and in the structure of the seed. They have many points 

 in common with Juglandaceae, but differ in their achlamydeous flowers 

 and superior ovary. They are aromatic shrubs or trees, with tonic and 

 astringent properties ; and wax, resin, and oil are obtained from them. 

 Myrica Gale, the Bog-Myrtle or Dutch Myrtle, yields an aromatic oil 

 and secretes wax j E. cenfera, the Wax-Myrtle, secretes a green wax ; 



