344 TREES OF NORTH AMERICA 



lateral heads in the spicate clusters sessile and embracing at maturity the 

 peduncle, usually persistent on the branches during the winter ; calyx of the 

 staniinate flower divided into 3-6 minute scale-like sepals slightly united at 

 the base, about half as long as the 3-6 cuneiform sulcate scarious pointed 

 petals ; stamens as many as the divisions of the calyx, opposite them, with 

 short nearly obsolete filaments, and elongated clavate 2-celled anthers, their 

 cells opening longitudinally, crowned by a capitate pilose truncate connective ; 

 calyx of the pistillate flower divided into 3-6, usually 4, rounded sej)als much 

 shorter than the acute petals ; stamens scale-like, elongated-obovate, pilose at 

 the apex ; ovaries as many as the divisions of the calyx, superior, sessile, oblong, 

 surrounded at the base by long ridged jointed pale hairs persistent round the 

 fruit, gradually narrowed into long simple bright red styles papillose-stigmatic 

 to below the middle along the ventral suture ; ovules 1 or rarely 2, suspended 

 laterally, orthotropous. Heads of fruit composed of elongated obovate akenes 

 rounded and obtuse or acute at the apex, surmounted by the persistent styles, 

 1-seeded, light yellow-brown ; pericarp thin, coriaceous. Seed elongated, 

 oblong, suspended ; testa thin and firm, light chestnut-brown ; embryo erect in 

 thin fleshy albumen ; cotyledons oblong, about as long as the elongated cylin- 

 drical erect radicle turned toward the minute apical hilum. A family of a 

 single genus. 



1. PLATANUS, L. Plane-tree. 



Characters of the family. 



A genus of six or seven species of eastern and western North America, Mexico, 

 Central America, and of southwestern Asia, all resembling each other except in the 

 form of the lobes of the leaves and the amount of pubescence on their lower surface, 

 in the pointed or obtuse apex of the akene, and in the number of heads of pistillate 

 flowers on their peduncle. 



Of the exotic species, the Old World Platanus orientalis, L., now a common street 

 tree in all the countries of temperate Europe, has been used as a shade-tree in the 

 eastern states and in California. 



Platanus is the classical name of the Plane-tree. 



CONSPECTUS OF THE NORTH AMERICAN SPECIES. 



Leaves broadly ovate, shallowly 3-5-lobed, the lobes mostly serrulate-toothed, truncate or 

 rarely wedge-shaped at the base ; head of fruit usually solitary. 



1. P. occidentalis (A, C). 

 Leaves deeply 5-lobed, the lobes entire, remotely and obscurely dentate or rarely sinuate- 

 toothed, truncate or rarely slightly cordate or wedge-shaped at the base ; heads of fruit 

 racemose. 2. P. racemosa (G). 



Leaves deeply 3-7-lobed, the lobes elongated, slender, entire or rarely remotely dentate, 

 deeply cordate or rarely wedge-shaped or truncate at the base ; heads of fruit racemose. 



3. P. Wrightii (H). 



1. Platanus occidentalis, L. Sycamore. Button-wood. 



Leaves broadly ovate, more or less 3-5-lobed by broad shallow sinuses rounded 

 at the bottom, the lobes broad, acuminate, sinuate-toothed, with long straight 

 or curved remote acuminate teeth, or entire, with undulate margins, truncate or 

 slightly cordate, or wedge-shaped and decurrent on the petioles at the base, thin 

 and firm, bright green on the upper surface, paler on the lower, glabrous with 

 the exception of a coat of pale pubescence along the midribs and principal veins 



