406 CROSSOSOMATACEAE 



rounded. Carpels as many as sepals, 1 -celled, surrounded by persistent hairs, and a 

 few staminodia. Style terminal, with the stigmatic surface on the ventral suture. 

 Ovule 1 or rarely 2, orthotropous. Fruit a dense globose head of achenes, with inter- 

 mingling hairs and staminodia. Seeds pendulous ; endosperm fleshy ; embryo axial, 

 straight. 



Comprising a single genus. An ancient genus, with a number of fossil species extending back to the 

 Cretaceous. Its relationship to other plant families is little understood. 



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

 Characters of the family. [Name, ancient.] 



A genus of 9 living species inhabiting the north temperate regions. Besides the following species, P. 

 Wrightii S. Wats, occurs in Arizona, New Mexico, and adjacent Mexico, P. occidentahs U in the eastern and 

 southern United States, and five other species in Mexico. Type species, P. orientals L. 



1. Platanus racemosa Nutt. California Plane-tree, Sycamore. Fig. 2358. 



Platanus racemosa Nutt. N. Amer. Sylva 1 : 47. 1842. 

 Platanus calif ornica Benth. Bot. Sulph. 54. 1844. 



A large widely branching tree, 10-25 m. high, with a trunk 1-1.5 m. in diameter; young 

 twigs densely stellate-tomentose, becoming glabrous and light brown the second year. Leaves 

 stellate-pubescent when young, usually glabrate in age, 10-15 cm. broad and scarcely as long, 

 palmately 5-lobed, rarely 3-lobed, truncate to below the middle or subcordate at base; lobes 

 acute, cuspidate; petioles shorter than the leaf -blades; stipules large on young twigs; staminate 

 heads several, 8-10 mm. in diameter; pistillate heads 3-5; 2-2.5 cm. in diameter in fruit. 



Along watercourses in the foothills and valleys, Upper Sonoran Zone; upper Sacramento Valley and 

 the interior valleys of the Coast Ranges south to northern Lower California. Type locality: vicinity of Santa 

 Barbara, California. Feb.-April. 



Family 63. CROSSOSOMATACEAE. 



Crossosoma Family. 



Glabrous shrubs, with alternate entire leaves. Flowers perfect, regular, solitary, 

 terminating short naked or leafy-bracted peduncles. Hypanthium turbinate-cam- 

 panulate, lined with a thin glandular disk. Sepals 5, broad, persistent, reflexed or 

 spreading in fruit. Petals 5, white, deciduous, attached to the rim of the hypanthium. 

 Stamens 15-50, inserted in several series on the thin disk lining the hypanthium; 

 filaments slightly dilated at base; anthers basifixed. Pistils 2-9, unicarpellate ; 

 ovules several, anatropous ; stigma capitate. Fruit composed of 2-9 follicles, sessile 

 or short-stipitate. Seeds several with a conspicuous fringed aril ; endosperm present ; 

 embryo curved. 



One genus and three or four species inhabiting southwestern United States and northern Mexico. 



1. CROSSOSOMA Nutt. Journ. Acad. Phila. II. 1 : 150. 1847. 



Characters of the family. [Name Greek, meaning fringe and body, in reference to the 

 fringed aril.] Type species, Crossosoma calif ornicum Nutt. 



Petals broadly obovate or orbicular-obovate, scarcely clawed; follicles many-seeded. 1. C. calif ornicum. 



Petals spatulate to oblong, distinctly clawed; follicles few-seeded. 2. C. Bigelovii. 



1. Crossosoma calif ornicum Nutt. Catalina Crossosoma. Fig. 2359. 



Crossosoma calif ornicum Nutt. Journ. Acad. Phila. II. 1: ISO. 1847. 



Shrub, 1-5 m. high with rather stout, grayish-brown branches. Leaves scattered, oblong, 

 2-7 cm. long, acutish or obtuse and mucronate at the apex, narrowed at base to a very short 

 petiole, pale green on both surfaces; sepals round-ovate, 7-8 mm. long; petals suborbicular, 

 about 12 mm. long, spreading ; stamens 40-50 ; follicles 3-7, rarely 9, about 15 mm. long, 3 mm. 

 thick, more or less recurved ; seeds 20-25, 3 mm. in diameter, shining. 



Hillsides and canyons, Upper Sonoran Zone; Santa Catalina and San Clemente Islands, southern California; 

 also on Guadalupe Island, Lower California. Type locality. Santa Catalina Island. Feb.-April. 



2. Crossosoma Bigelovii S. Wats. Bigelow's Crossosoma. Fig. 2360. 



Crossosoma Bigelovii S. Wats. Proc. Amer. Acad. 11: 122. 1876. 



Straggly shrub, 1-2 m. high, with rather slender spreading branchlets bearing scattered 

 leaves and also short stubby ones bearing fascicles of leaves. Leaves elliptic to oblong-obovate, 

 10-15 mm. long, firm, apiculate, gray-green; sepals 4 mm. long and about as broad; petals 



