162 



ROSACEAE 





h. Ovary hccoming a drxtpe ; trees or shnihs with simple leaves and caducous stipules. — 



Tribe Drupeae. 



Pistils 5; drupes 1 to 5; flowers dioecious 24. Osmaeonia. 



Pistil 1; drupe solitary; flowers perfect 25. Prunus. 



B. Ovary inferior, 2 to 5-ceUed, enclosed in and mostly adherent to the fleshy cal3rx-tube; 

 fruit a pome ; trees and shrubs. — Tribe Pomeae. 



Leaves compound ; flowers in compound corymbs; fruit coral red, berry -like 26. SoRBtrs. 



Leaves simple. 



Foliage evergreen, coriaceous; flowers small, numerous, in a corymbose panicle; fruit bright 



red, berry like 27. Photinia. 



Foliage deciduous. 



Flowers in corymbs. 



Branches not thorny; styles united at base; fruit a pome 28. Pyrus. 



Branches with stout thorns; styles distinct; fruit drupe-like, containing 2 to 5 bony 



stones 29. Crataegus. 



Flowers not in corymbs ; branches not thorny ; fruit berry-like, containing several carti- 

 laginous seeds. 



Flowers 1 to 3 in a sessile umbel; petals spreading; styles 2 30. Peraphyllum. 



Flowers several in a receme; petals erect; styles 5 31. Amelanchier. 



1. LYONOTHAMNUS Gray 



Evergreen tree with thin bark exfoliating in long loose strips and with opposite 

 dimorphic petioled leaves. Flowers numerous in a much-branched terminal pan- 

 icle. Calyx-lobes 5. Petals 5 and stamens 13 to 16, inserted on the margin of the 

 woolly disk lining the hemispheric calyx-tube. Pistils 2, distinct, each with a 

 spreading style and capitate stigma. Fruit consisting of two woody 4-seeded 



carpels dehiscent ventrally and partly dehis- 

 cent dorsally. — Species 1. (The sur-name of 

 W. S. Lyon of Los Angeles, the discoverer, com- 

 bined with Greek thamnos, shrub.) 



1. L. floribundus Gray. Catalina Iron- 

 wood. (Fig. 158.) Slender tree 20 to 55 feet 

 high, with narrow crown ; leaves Oleander-like, 

 linear, nearly entire or pinnately cut, petioled, 

 3 to 7 inches long, or often pinnately compound 

 with 2 to 5 leaflets similar in shape and size to 

 the simple leaves; flowers white, 3 lines broad, 

 in terminal clusters 3 to 6 inches broad; petals 

 orbicular, sessile, white, crenulate-edged. 



Canon walls, 500 to 2000 feet : Santa Cata- 

 lina Isl. May-July. 



Field note. — The leaves are dimorphic; in one 

 form the leaf is lanceolate and essentially entire, that 

 is, a simple leaf ; in the other form the leaf is pinnately 

 divided into 3 to 5 lanceolate pinnae 1^/^ to 4^/4 inches 

 long, the pinnae regularly and deeply divided into 

 broad obliquely obtuse segments 2 to 5 lines long 

 (asplenioid). This latter form (here called "com- 

 pound" for convenience) represents the var. aspleni- 

 folia Bdg. which is the only form found on Santa Cruz, 

 Santa Eosa and San Clemente islands. On Santa Cata- 

 lina, the first named or undivided type is found. Inter- 

 grades, however, between the two forms occur on Santa 

 Catalina Island. These intergrades consist of the fol- 

 lowing states: (a), the simple lanceolate leaf has the basal part cut to the midrib into small lobes; 

 (b), the simple lanceolate leaf is irregularly segmented throughout; (c), the simple lanceolate 

 leaf is replaced by 2 to 5 pinnately arranged lanceolate segments, the segments similar in shape 

 and size to the simple leaf, some of them often distinct or essentially so; (d), leaf "compound" 

 as in c, with the segments more or less irregularly asplenioid. Finally the typical "asplenifolia" 

 foliage may be found on Santa Catalina Island, though but rarely. 



Fig. 158. LYONOTHAMNUS FLORIBUN- 



Dus Grav. a, fl. branchlet, X %; h, 

 "compound" leaf, X % ; c, fl., X 3. 



