488 SYSTEMATIC BOTANY. 



Flowers regular, unsymmetrical. Sepals and petals imbricated, 

 the latter without any appendages on their inside. Stamens 

 hypogynous, on a fleshy disk ; anthers bursting longitudinally ; 

 ovary superior, 2-celled. Fruit a samara, 2-celled, each cell 

 containing 1 or 2 seeds. Seeds without an aril, exalbuminous ; 

 embryo, curved with an inferior radicle. 



Distribution, S^c. — The plants of this order are natives of the 

 temperate parts of Europe, Asia, and North America. None 

 have been found in Africa and the southern hemisphere. Ex' 

 amples : — Acer, Negundo, Dobinea. There are 3 genera, and 

 60 species. 



Properties and Uses. — These plants are chiefly remarkable for 

 their saccharine sap. Their light and handsome timber is also 

 much used in turnery, for certain parts of musical instruments, 

 &c. ; and their bark is astringent, and is employed in different 

 districts by the dyer, in the production of yellow, reddish-brown, 

 and blue colours. The most important genus is 



Acer Thus A. sacckarinu?}?, is the Sugar Maple. The Maple Sugar of 



America is obtained from this tree, by making perforations into its trunk at 

 the commencement of spring, and boiling down the saccharine sap which then 

 exudes to the crystallizing point. A few years since as much as 45 millions 

 of pounds of Ma|)le Sugar were annually produced in North America, but 

 the quantity diminishes yearly, in consequence of the destruction of the 

 native forests. A. dasycarpum and other species also yield sugar. The bark 

 of .<4. saccharimim has been used in America in the production of a blue dye, 

 and as an ingredient in the manufacture of ink. A. campestre and A. Pseudo- 

 platanus, are common trees in Britain, and afford useful timber ; the latter 

 is commonly known under the names of the Sycamore, Greater Maple, and 

 Mock-plane. It derives the latter name from the resemblance of its leaves to 

 those of the true Plane-tree. Its wood is also used for making charcoal. 



Natural Order 45. Hippocrateace^. — The Hippocratea Or- 

 der. — General Character. — Shrubs, frequently with a climb- 

 ing habit, and generally smooth. Leaves opposite, simple, with 

 small deciduous stipules. Calyx 5-lobed, very small, persistent, 

 imbricated. Petals 5, hypogynous, imbricated. Stamens 3, 

 monadelphous; the coherent filaments forming a disc-like cup 

 round the ovary; anthers with transverse dehiscence. Ovary 

 superior, 3 -celled ; style 1 ; stigmas 1—3. Fruit either baccate, and 

 1 — 3-celled, or consisting of three samaroid carpels. Seeds de- 

 finite, attached to axile placentas, exalbuminous ; embryo straight ; 

 cotyledons flat, and of a somewhat fleshy nature ; radicle inferior. 



Diagnosis. — Shrubs with opposite simple leaves, and small 

 deciduous stipules. Flowers small, regular, and unsymmetrical. 

 Sepals and petals 5, hypogynous, imbricated, the former per- 

 sistent. Stamens 3, hypogynous monadelphous; anthers with 

 transverse dehiscence. Ovary 3-celled; style 1. Fruit baccate, 

 or consisting of 3 samaroid carpels. Seeds definite, exalbumi- 

 nous; embryo straight; radicle inferior. 



Distribution, Sfc.—lL\\(iy abound principally in South America; 

 some are also found in Africa and the East Indies. Examples : — 

 Hippocratea, Tontelca, Diplesthes. There are 6 genera, and 

 86 species. 



