Keys to Nature
Key to the Apocynaceae (dogbanes and milkweeds) of Minnesota

© Peter M. Dziuk, Butterfly milkweed - Keys to Nature Project

Key to the Apocynaceae (dogbanes and milkweeds) of Minnesota
Bega Inaho, Ann Kennedy
This key was created as part of a Minnesota Flora class. We started with a list from Comprehensively Annotated Checklist of the Flora of Minnesota, version 2011.3 ->18 of 23 MN Apocynaceae are keyed. Plants excluded from key: 1) Apocynum androsaemifolium x Apocynum cannabinum. A cross breed with no USDA name 2)Asclepias purpurascens L. - known only from Wabasha County historical collection from 1883. 3)Asclepias quadrifolia Jacq -reported for Minnesota by USDA-NRCS but no specimens at MIN; known from IA, IL. 4)Cynanchum louiseae Kartesz & Gandhi reclassified to Vincetoxicum nigrum. 5)Cynanchum nigrum (L.) Pers. reclassified to Vincetoxicum nigrum.


Key Structure:
1a. Plant vine or shrub -2
1b. Plant erect perennial or biennial -3

2a. Plant climbing vine - Vincetoxicum nigrum
2b. Plant trailing perennial shrub - Vinca minor L.

3a. Leaves whorled or (mostly) alternate -4
3b. Leaves opposite -7

4a. Leaves whorled - Asclepias verticillata L.
4b. Leaves (mostly) alternate -5

5a. Steam smooth or lightly hairy- Asclepias stenophylla A. Gray
5b. Steam hairy -6

6a. Flower color orange to yellow- Asclepias tuberosa L.
6b. Flower color pale green to cream with purplish tips - Asclepias lanuginosa

7a. Leaf shape more lance like -8
7b. Leaf shape more oval -10

8a. Flower color pink to red - Asclepias incarnata L.
8b. Flower color pale green -9

9a. Flowers grouped in erect stalked umbles -Asclepias hirtella (Pennell) Woodson
9b. Flowers grouped in drooping stalkless umbles - Asclepias viridiflora

10a. No leaf stalk (petiole) or less than 6mm -11
10b. Leaf stalk greater than 6mm -14

11a. Flowers white, green,or yellow -12
11b. Flowers pink or purple -13

12a. Leaf edges wavy - Asclepias amplexicaulis Sm.
12b. Leaf edges smooth - Apocynum sibiricum Jacq.

13a. Leaf and steam hairless - Asclepias sullivantii
13b. Leaf underside and steam hairy - Asclepias speciosa Torr.

14a. Flower bell or tube shaped -15
14b. Flower with 5 petals angled down and 5 tips pointing up -16

15a. Flowers white to pink with pink stripes - Apocynum androsaemifolium L.
15b. Flowers white to pale green - Apocynum cannabinum L.

16a. Main stem smooth - Asclepias exaltata
16b. Main stem hairy -17

17a. Prominent leaf midrib creamy white to pink- Asclepias syriaca L.
17b. Leaf midrib not prominent, pale green to green - Asclepias ovalifolia Decne


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This page was last modified on: Wed, 2 Sep 2015 09:49:46 -0500.