FOREST TREES OF THE PACIFIC SLOPE. 331 



Tolerance. — Exceedingly tolerant of shade throughout life, but partial or fall over- 

 head light necessary for best height growth. 



Rephodiction. — Fairly abundant seeder ; locally often heavily laden with fruit. Seed 

 of moderately high rate of germination and of very transient vitality; germinates shortly 

 after falling to ground. Clumps of seedlings frequent in dense or partial shade, whtre they 

 grow rapidly. 



Family SAXIFRAGACE^l. 



A very large group of mainly herbaceous plants and a few trees and shrubs 

 of world-wide distribution. They receive their name (which means, literally, 

 stone breaking) because they mainly inhabit dry or wet rocky situations, and 

 are particularly prone to alpine habitats. The flowers have both male and 

 female organs in the same bloom; the leaves occur singly or in pairs (one op- 

 posite another) ; and the very minute seeds are borne in small, clustered cap- 

 sules. The family is represented in the United States by the following single 

 genus, the one species of which is a tree described as recently as 1877. 



LYONOTHAMNUS. 



Lyonothamnus is a genus containing the only tree species of the family 

 indigenous to the United States or North America. It is confined to the Cali- 

 fornia coast islands, Santa Catalina, and Santa Cruz, in the former of which 

 it was discovered in 1884 by William S. Lyon, forester of the first board of 

 forestry created in California. The genus was named in his honor. The char- 

 acters of this genus are given under the one species now known. 



Western Ironwood. 

 Lyonothamnus floribundus Gray. 



DISTINGUISHING CHARACTERISTICS. 



Little is known of the trunk and crown form and silvical habits of western 

 ironwood. In open, rocky sites it is only a small shrub ; most commonly a tall 

 shrub with clustered stems, occasionally a shrubby tree from 20 to 25 feet high 

 and from 4 to 8 inches in diameter. The bark, with its deep reddish color and 

 its thin flaky layers, is very characteristic. A number of bark layers, broken 

 and separated, often hang in long shreds. The twigs are clear, shiny red. The 

 fern-like evergreen leaves are opposite and vary greatly from an undivided 

 form (fig. inn) to one split into several subdivisions (fig. 154). Individuals 

 with only one or the other of these types occur, but trees are also found bearing 

 both types of foliage, showing that the species lias remarkably variable foli- 

 age. The small flowers, produced in flat-topped, branched clusters, open in early 

 summer, and the fruit, two very small, closely joined, bristly glandular capsules, 

 each witli four minute, long seeds, are ripe the following autumn. The cap- 

 sules split open of their own accord and gradually the seeds are liberated. 



Wood, very heavy, dense, line-grained, and exceedingly hard. The name iron- 

 wood was doubtless given because of the hardness of the wood. It is distinctly 

 red, with a slight yellowish tint. It is suitable for ornamental or fancy wood- 

 work, but is not known to have any economic use. 



The limited range anil rather rare occurrence of large stems are likely to 

 prevent the species from ever becoming important commercially. Its chief value 

 must lie in assisting to form protective cover on steep, dry. rocky slopes, where 

 few other trees and shrubs can maintain themselves. 



«T. S. Brandegee, Zoe, I, 111. 



