242 Karl M. Wiegand and Arthur J. Eames 



e. Styles more or less united ; hypanthium generally open ; flesh of the fruit 

 without grit cells. 7. Malus 



d. Inflorescence plainly corymbose-paniculate; flowers small, 1.5 cm. in diam. 

 or less (in exotics sometimes 2 cm.) ; fruit small, 5-15 mm. in diam. 

 (rarely up to 30 mm. in exotics) ; leaves simple or compound. 

 e. Leaves pinnate; styles free. 8. Sorbus 



e. Leaves simple; styles usually united below. 9. Aronia 



c. Cells of the ovary, at least in fruit, twice as many as the styles, through 

 intrusion of the wall ; flowers in racemes, white. 10. Amelanchier 



b. Mature carpels very hard and bony, usually 1-ovuled; leaves usually incised; 

 plant usually thorny; flowers white. 11. Crataegus 



a. Ovary superior ; carpels 1-many. 



b. Carpels 2-several, distinct; herbs or shrubs with simple or compound leaves. 

 c. Fruit follicular or indehiscent; carpels 2-many-ovuled (in no. 4 1-seeded in 

 fruit). 

 d. Carpels bladdery-inflated in fruit ; shrubs with broad, lobed, simple leaves, 

 and numerous small flowers; bark shreddy. 1. Physocarpus 



d. Carpels not inflated. 



e. Flowers very small and numerous ; petals oval. 

 /. Leaves simple; shrubs. 2. Spiraea 



/. Leaves pinnate. 

 g. Leaflets all lanceolate, finely serrate, straight-veined ; stipules narrow ; 



plants suffrutescent. 3. Sorbaria 



g. Leaflets generally broader, the terminal ones larger, all irregularly 

 incised or lobed; stipules broad; plants herbaceous. 



4. FlLIPENDULA 



e. Flowers few, large; petals strap-shaped; leaves 3-foliolate; herbs. 



5. Gillenia 

 c. Fruit an achene or a drupe; carpels 1-ovuled. 



d. Fruits not inclosed permanently in the receptacle ; leaves simple or compound. 

 e. Ovaries ripening as achenes ; bractlets present between the sepals ; plants 

 herbaceous, with compound leaves. 

 /. Styles not elongated in fruit. 

 g. Receptacle much enlarged in fruit, pulpy, red or white; leaves 3- 

 foliolate. 

 h. Flowers white ; bractlets subentire ; fruit usually acid and of good 

 flavor ; leaflets sharply serrate ; plant scapose, with flowerless and 

 almost leafless runners. 12. Fragaria- 



h. Flowers yellow ; bractlets broad, 3-lobed ; fruit nearly tasteless ; 

 leaflets crenate; plant indistinctly scapose, the leafy runners flower- 

 bearing. 13. Duchesnea 

 g. Receptacle not enlarged, dry. 

 h. Achenes 2-6 (10) ; plants scapose; leaves 3-foliolate; flowers yellow. 



14. Waldsteinia 

 h. Achenes many; plants caulescent; leaves palmately 3-7-foliolate, 



or pinnate ; flowers white, cream, yellow, or purple. 



15. Potentilla 



/. Styles elongated in fruit, hooked, persistent, often plumose ; flowers 

 white, purple, or yellow. 16. Geum 



e. Ovaries ripening as drupelets ; bractlets between the sepals absent. 

 /. Drupelets many, on an enlarged convex receptacle ; plants herbaceous 

 or woody, often prickly, prostrate or erect, often tall ; leaves simple 

 or compound; flowers purple or white. 17. Rubus 



/. Drupelets few, at the bottom of the concave receptacle, nearly dry; 

 plants very low, herbaceous, creeping ; leaves simple : flowers white. 



18. Dalibarda 



