California Lilac 679 



yellow-green on the under side, toothed or nearly entire-margined, the low teeth 

 gland-tipped, not bristly. The small polygamous or dioecious flowers open from 

 March to May; the 4 lanceolate pointed calyx-lobes are about as long as the ca- 

 lyx-tube; there are no petals; the 4 stamens of the staminate flowers are some- 

 what shorter than the calyx-lobes. The fruit is scarlet, broadly obovoid, about 5 

 mm. long, containing 2 grooved nutlets. 



Rhamnus cathartica Linnaeus, the Purging buckthorn of Europe, has been 

 widely planted for hedges in the eastern United States, and is locally naturalized. 

 It has thorny branches, petaliferous flowers, and black fruit containing 3 or 4 

 nutlets. Usually a tall shrub, planted trees are known up to 9 meters high, with 

 short trunks 3.5 dm. thick. 



VI. CALIFORNIA LILACS 



GENUS CEANOTHUS LINN^US 



f]OT fewer than 35 or 40 species of Ceanothus are known, natives of the 

 United States, British America, and northern Mexico. Most of them 

 are shrubs, some, such as the New Jersey tea {Ceanothus americanus 

 Linnaeus), the type of the genus, widely distributed in eastern North 

 America, not over 6 or 7 dm. high; but at least 3 of the California species form 

 small trees, and several others which are normally shrubs sometimes become tree- 

 like. 



They have alternate stalked leaves, often strongly 3-ner\'ed, and small perfect 

 flowers, usually very numerous in large clusters. The calyx is 5-lobed, the lobes 

 curved inward; there are 5 hooded and clawed petals, each more or less enfolding 

 a stamen with a filiform filament; the 3-lobed and 3-celled ovary is sunk in the 

 disk and adnate to it, and there is'a single ovule in each cavity. The fruit is dry, 

 3-lobed or nearly round, sphtting when ripe into 3 valves. 



The generic name is Greek, first applied to these plants by Linnaeus, but used 

 by the ancient authors for some wholly different group. 



The North American arborescent species may be distinguished as follows: 



Leaves smooth, or but little pubescent beneath. 



Twigs unarmed. i. C. thyrsiflorus. 



Twigs tipped with spines. 2. C. spinosus. 



Leaves densely white-tomentose beneath. 3. C. arboreus. 



I. CALIFORNIA LILAC — Ceanothus thyrsiflorus Eschscholtz 



This, the largest of the genus, sometimes attains a height of about 12 meters, 

 with a trunk 3 or 4 dm. in diameter, but is usually much smaller and commonly 

 a shrub. It is abundant on hillsides and along streams in western California, 

 and is not known to grow naturally except in that State. It, its hybrids, and deriv- 

 atives under cultivation, are largely planted in European and Califomian parks 



