242 



PLATANACEAE. 



Vol. II. 



Family 53. PLATANACEAE Lindl. Nat. Syst. Ed. 2, 187. 1836. 



Plane-tree Family. 



Large trees, with thin exfohating bark, alternate petioled palmately lobed and 

 veined leaves, the hollowed petiole bases enclosing the buds for the following 

 season, and very small green monoecious flowers in dense globular heads. Recep- 

 tacle somewhat fleshy. Flowers very small, bracted ; calyx and corolla appar- 

 ently none. Staminate flowers with 3-8 stamens ; filaments short ; connective 

 broad, dilated ; anthers oblong or linear, longitudinally dehiscent. Pistillate flowers 

 with 2-9 distinct pistils and several staminodes ; ovary linear, i-celled; style 

 elongated ; stigma lateral. Ripened head of fruit composed of very numerous 

 narrowly obpyramidal nutlets which are densely pubescent below with long nearly 

 erect hairs. Seed pendulous; endosperm thin; cotyledons linear. 



The family contains only the following genus, comprising some 8 species, natives of the north 

 temperate zone. Its relationship to other families is doubtful. 



I. PLATANUS [Tourn.] L. Sp. PI. 999. 1753. 

 Characters of the family. [Name ancient.] 



Besides the following species, 2 others occur in the western United States and 3 in Mexico. 

 Type species : Platanus orienlalis L. 



I. Platanus occidentalis L. Button-wood. Button-ball. Plane-tree. Fig. 2212. 



Platanus occidentalis L. Sp. PI. 999. 1753. 



A large tree; maximum height about 130° and 

 trunk diameter 14° ; outer bark freely peeling off 

 in thin plates, uncovering the bright white inner 

 layers. Leaves orbicular, or wider than long, 

 4'-9' wide when mature, cordate or truncate at 

 the base, 3-S-lobed, densely floccose-pubescent 

 with whitish branched hairs when young, less so 

 above and becoming nearly glabrous when old, 

 the lobes mostly large, sharply serrate, or rarely 

 entire ; petiole mostly shorter than the blade ; 

 stipules with broad spreading toothed borders, 

 conspicuous on young shoots ; fruiting heads i' 

 in diameter, usually solitary, hanging on a long 

 peduncle, persistent through the winter, the nut- 

 lets at length scaftered by the wind. 



Along streams and in wet woods, Maine to On- 

 tario and Minnesota, Florida, Kansas and Texas. 

 Wood hard, weak, difficult to split, reddish brown ; 

 weight per cubic foot 35 lbs. The largest tree of 

 east America ; often called sycamore. The outer 

 bark of the lower part of old trunks does not freely 

 exfoliate. False sycamore. Water-beech. May. 



Family 54. ROSACEAE B. Juss. Hort. Trian. 1759. 

 Rose Family. 

 Herbs, shrubs, or trees, with alternate (in some exotic genera opposite), 

 simple or compound leaves, and regular perfect or rarely polygamo-dioecious 

 flowers. Stipules commonly present, sometimes large. Calyx free fromoradnate 

 to the ovary, s-lobed (rarely 4-9-lobed), often bracteolate. Disk adnate to the 

 base of the calyx. Petals equal in number to the calyx-lobes, distinct, or none. 

 Stamens usually numerous, distinct; anthers small, 2-celled. Carpels i-oo, dis- 

 tinct, or adnate to the calyx. Ovary i-celled or rarely imperfectly 2-celled; style 

 terminal or lateral. Ovules i, 2, or several, anatropous. Fruit various, mostly 

 follicles or achenes ; endosperm none, or rarely copious. 



A family comprising about 75 genera and more than 1200 species, of wide geographic distribution. 

 A. Fruit of 1-5 dehiscent follicles. 

 * Carpels alternate with the sepals ; stipules deciduous or none. 

 Carpels, if more than i, united below; seeds with endosperm (Neillieae). i. Opulaster. 



Carpels normally 5, distinct ; seeds without endosperm (Spiraeeae). 



Flowers perfect ; shrubs with simple leaves. 2. Spiraea. 



Flowers dioecious ; tall herbs with pinnately 2-3-compound leaves. 3. Anincus. 



