Apocynum androsaemifolium

Spreading Dogbane

Flower Longitudinal Section

Lac des Isles in Meadow Lake Provincial Park  
11-August-2008

Note that the stamens converge to form a cone around the style and stigma.  Note also there are two carpels which are distinct below but which fuse to a single style above.  Finally, note the recurved corolla lobes.

There are three species of Apocynum found in the Canadian prairies: A. androsaemifolium, A. cannabinum, and A. medium.  A. medium is considered to be a hybrid of the first two species.  The answers colored in red below are those which separate A. androsaemifolium from A. medium.  The ratio of petal length to sepal length is important in separating all three species; that answer is colored green.

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

leaves drooping or spreading; NOT [leaves ascending or spreading]

flower clusters both terminal and axillary; NOT [flower clusters at the ends of leafy branches only]

flower clusters flowering simultaneously; NOT [central clusters opening much earlier than the others]

flowers nodding; NOT [flowers upright or spreading]

petals three times as long as sepals; NOT [petals twice as long, or less than twice as long, as sepals]

corolla-lobes recurved; NOT [corolla lobes spreading or ascending]

corolla pinkish; NOT [corolla greenish to whitish]

seeds 2.5-4 mm long; NOT [seeds 4-6 mm long]

 

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

herbs; NOT [shrubs or trees]

plants green or with some chlorophyll; NOT [plants parasitic or saprophytic, without chlorophyll]

plants WITH milky juice

flowers not in heads or spikes; NOT [flowers in long or short spikes]; NOT [flowers in heads or in form resembling a head]

flowers with two floral rings, but with the petals wholly or partly united forming a tube or bell]

corolla regular; NOT [corolla irregular]

stamens distinct; NOT [stamens united]

pollen grains separate; NOT [pollen grains united into a mass]

ovary superior; NOT [ovary inferior]

styles united; NOT [styles distinct]