Amelanchier alnifolia
 
Saskatoon

Flower Top, Stage 1

Struthers Lake Regional Park
27-May-2011

If you look carefully, you should be able to count 20 stamens.  Some of them have large, unopened anthers while others have smaller, opened anthers.  Flora of the Great Plains states that this species has 15-20 (uncommonly 10) stamens.

Alnifolia: Answers to key questions in Budd's Flora leading to this species. 

pedicels short, mostly 6-8 mm; NOT [pedicels long, the lower ones 15-20 mm long]

 

Amelanchier: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus. 

shrubs or trees; NOT [herbs, or with a woody base and otherwise herbaceous]

plants taller; NOT [creeping dwarf shrubs]

stems not thorny; NOT [stems with stout thorns]

leaves simple; NOT [leaves compound or lobed]

leaves serrate or toothed; NOT [leaves entire] (BF)

leaves entire to toothed; NOT [leaves mostly incised-toothed or lobed] (FOA)

flowers usually more numerous; NOT [flowers solitary on a long peduncle]

NOT [flowers in broad compound corymbs]

ovary inferior, enclosed in and adnate to the hypanthium; NOT [ovary or ovaries superior, hypanthium free from the ovary]

fruit fleshy; NOT [fruit a leathery follicle]

fruit a berry-like pome with several seeds; NOT [fruit a red or black drupe with a single stone]

 

Rosaceae: Answers to key questions in Budd's Flora  leading to this family. 

herbs; NOT [shrubs or trees]

plants terrestrial or semiaquatic; NOT [plants aquatic, leaves submerged or floating]

plants NOT with colored milky juice

plants with more than one normal leaf

some or all leaves alternate; NOT [leaves opposite, whorled, or basal]

leaves with stipules; NOT [leaves without stipules, or having glands]

flowers with two floral rings, and with each petal distinct from the others

flowers regular in shape; NOT [flowers irregular in shape]

calyx regular; NOT [calyx irregular, some sepals smaller than others]

stamens usually separate or partly so, not in a column; NOT [stamens numerous, united into a column]

ovary of one or more carpels, either separate or enclosed by a fleshy receptacle; NOT [ovary of 5 united carpels]