Utah Native Milkweed
Identifying Milkweed Species
For a quick guide you can print to take with you in the field, see our "Identifying Milkweed in Utah" resource.
DISTINGUISHING CHARACTERISTICS OF MILKWEED
Note that milkweed is the only host plant for the monarch caterpillar.
Distinguishing Characteristic #1
Umbrella-like flowering head (multiple flowers originate from one point like the base of an umbrella)
Distinguishing Characteristic #2
Milky sap called latex - visible when a leaf is torn
Distinguishing Characteristic #3
Unique flower morphology include:
Re-flexed petals when flowers mature
Flower parts consisting of 'hoods' and 'horns' around the reproductive features of the flower that influences pollinator behavior
NATIVE MILKWEED SPECIES IN UTAH
Click HERE for a Powerpoint Presentation on milkweed and distribution maps of all Utah native species.
At least fifteen species of milkweed are known to be native to Utah. Utah's native milkweed species include the following Asclepias species, in alphabetical order:
A. asperula (antelope horns or spider milkweed) - Flowers May to July - Common
A. cryptoceras (pallid or jewel milkweed) - Flowers April to June - Uncommon
A. cutleri (Cutler's milkweed) - southeast Utah only - Flowers May to June - Rare
A. engelmanniana (Engleman's milkweed) - closely related to A. rusbyi
A. erosa (desert milkweed) - Washington County only - Flowers May to Septemeber - Rare
A. hallii (Hall's milkweed) - Flowers May to September - Rare
A. incarnata (swamp milkweed) - Flowers July to September - Common
A. involucrata (dwarf milkweed) / closely related to Asclepias macosperma - Flowers April to July - Uncommon
A. labriformas (Utah milkweed) - Flowers May to July - Uncommon
A. latifolia (broadleaf milkweed) - southern Utah - Flowers June to July- Uncommon
A. rusbyi (Rusby's milkweed) - southern Utah - Flowers in June and July - Uncommon
A. speciosa (showy milkweed) - Flowers May to July - VERY common
A. subverticillata (horsetail milkweed) - southern Utah in disturbed sites - Flowers July- October - Common
A. tuberosa (butterfly weed) - Flowers May to August - Uncommon
A. welshii (Welch's milkweed) - Kane County in sand dunes - Flowers June to August - Rare
A. speciosa (showy milkweed) - Flowers May to July - VERY common
A. incarnata (swamp milkweed) - Flowers July to September - Common
A. tuberosa (butterfly weed) - Flowers May to August - Uncommon
A. asperula (antelope horns or spider milkweed) - Flowers May to July - Common
A. subverticillata (horsetail milkweed) - southern Utah in disturbed sites - Flowers July to October - Common
A. labriformas (Utah milkweed) - Flowers May to July - Uncommon
A. cryptoceras (pallid or jewel milkweed) - Flowers April to June - Uncommon
A. erosa (desert milkweed) - Washington County only - Flowers May to Septemeber - RARE
A. involucrata (dwarf milkweed)/ closely related to Asclepias macosperma- Flowers April to July - Uncommon
A. latifolia (broadleaf milkweed) - southern Utah - Flowers June to July- Uncommon
A. ruthiae (Ruth's milkweed)
A. welshii (Welch's milkweed) - Kane County in sand dunes - Flowers June to August - RARE
A. hallii (Hall's milkweed) - Flowers May to September - RARE
A. engelmanniana (Engleman's milkweed) - closely related to A. rusbyi
A. cutleri (Cutler's milkweed) - southeast Utah only - Flowers May to June - RARE
MORE EASY WAYS TO IDENTIFY NATIVE MILKWEED IN UTAH
Utah's most familiar milkweed species is Asclepias speciosa (showy). However, other species can be found readily in areas like Vernal, Moab, the Great Basin area.
Several free apps are available to download that can help you identify a particular species of milkweed.
If you choose to use the Monarch SOS app, it can help identify which species of milkweed you have discovered. When you access the app, please include a photo so others can help confirm the species for you.
The iNaturalist app will also recommend species based on the photo you enter. The greater community can help confirm the species if you are unsure.