440 ROSEACE^. 



Lo.NG-LEAF or SwAMP Sekvice-berry, .4.. obovalis (Michx.; Ashe. A small tree or i^hrub 

 found iu swamps and moist localities of northern states and northward. Leaves obloug to 

 broad-elliptical, iVs-^ in. long, mostly rounded or obtuse at base, acute or rounded at apex, 

 finely serrate, whitish wooly when they unfold, nearly glabrous at maturity. Flowers in dense 

 racemes IVo-^Vij in- long, at lirst hairy but becoming glabrous; petals about % in. long. 

 Fruit depressed globose, Vs iu. in diameter, from red to dark purple, glaucous. 



Western Service-berry or June-berry, A. ahufolia Xutt. A small tree of the Pacific 

 coast region ranging eastward to Manitoba and northern Michigan, but is only a shrub east 

 of the Rocky Mountains. It is characterized by having thickish broad elliptical to suborbicular 

 leaves obtuse to truncate and coarsely dentate at apex, and short rather dense racemes. 



THE HAWS OR THORNS. Genus CRAT^GUS L. 



The Haws, Thorns. Hawthorns or Thorn-apples, as they are variously called, are gen- 

 erally low wide-spreading trees or shrubs, with very strong tortuous branches armed with stiff 

 sharp thorns (though sometimes unarmed), with somewhat zigzag branchlets and usually 

 with dark or gray scaly bark. They are mostly confined to north temperate regions, with 

 the bulk of distribution in eastern United States. Twenty years ago scarcely a score of 

 species were recognized in America and fewer abroad, but it was thought that many of the 

 species presented almost innumerable forms. 



Within the past few years much attention has been paid to the subject, and now the list 

 of named species numbers more than six hundred. The validity of many of these, however, 

 is extremely problematical, as observers working in different localities have made observations 

 and assigned names quite independently of each other, and when the studies have been more 

 extended and results compared, doubtless many of the names must be relegated to synonymy. 

 The value of certain characters, too, upon which to determine specific rank, are matters of 

 controversy, and can only be determined by more extensive observation and agreement. 

 Extensive experiments are being conducted, notably at the Arnold Arboretum, under the 

 direction of Prof. C. S. Sargent, to determine how far seedling plants will present the 

 characters of their parents, and the results will be looked upon with much interest. 



Due to the present unsettled condition of the subject it is impossible to present the 

 genus with the completeness accorded the other genera, and it lias been decided to take up and 

 illustrate only a few of the most distinct or common species, defining them as outlined by 

 I'rof. Sargent. 



Leaves conduplicate in the bud, simple, petiolate, generally serrate, and often also lobed, 

 especially on vigorous shoots, deciduous : stipules caducous or on vigorous shoots often 

 foliaceous. Floicers in simple or compound corymbs terminating short lateral leafy branch- 

 lets, lowermost pedicels of a cluster often from the axils of leaves : calyx obconic with .5 

 acute reflexed mostly persistent lobes and tube adnate to the carpels: petals .">, white and 

 l)inkish, spreading and inserted on the throat of the calyx ; stamens normally 5 in one row 

 and alternate with the petals or 10 in 5 pairs, or 15 in 2 rows, those of the outer row in 

 pairs, or 20 in 3 rows, or 25 in 4 rows ; filaments subulate, incurved ; anthers pale yellow to 

 nearly white, or from pink to dark rose and purple ; ovary inferior, 1-5-celled with ] or 2 

 ovules in each cell: styles 1-5, distinct, persistent. Fruit a pome from short globose to oblong 

 or i)ear-shaped, mostly from red to yellow (sometimes blue or black) with 1-5 bony carpeis 

 united below and each containing usually a single erect compressed seed. 



The name is from the Greek word for strength, referring to the toughness of the wood. 

 For species see pp. 2'i't-261. 



THE PLUMS AND CHERRIES. Genus PRUXUS B. & H. 



Trees and shrubs with peculiar l)itter astringent properties, many containing prussic 

 acid and exuding a gum from the bark when wounded. They are of general distribution 

 throughout the temperate and tropical regions of the northern hemisphere and many repre- 

 sentatives are of great economic value. There are about one hundred twenty species of which 

 some twenty-five or thirty occur in the United States, eighteen of these being arborescent. 



Leaves alternate, simple, petiolate. conduplicate or convolute in the bud. deciduous or 

 persistent, serrate (sometimes entire): petioles often glandular: stipules small, caducous; 

 winter buds with closely imbricated scales, the innermost accrescent. Flowers regular, 

 perfect; calyx inferior, deciduous, with 5 lobes imbricated in the bud and thin annular disk; 



