Horsetail Milkweed
Asclepias subverticillata
- Native to:
- Mexico, United States
Braderfly
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Apocynaceae
- Genus:
- Asclepias
- Species:
- Asclepias subverticillata
- USDA Symbol:
- ASSU2
Growth Characteristics
- Life Cycle:
- Perennial
- Growth Habit:
- Forb/herb
- Height:
- 90 cm
- Light Requirements:
- Full Sun
- Drought Tolerance:
- High
- Bloom Months:
- may,jun,jul,aug,sep
- Bloom Colors:
- white, greenish-white
Wildlife Benefits
- Bees:
- ★☆☆☆☆ Documented bee visitation (GBIF)
- Butterflies & Moths:
- ★☆☆☆☆ Documented Lepidoptera association (GBIF)
Keystone Species Ranking
- Caterpillar Keystone:
- ★★☆☆☆ Butterfly & moth species supported by this genus (NWF)
Reported Fauna Sightings
Bees: Brown-belted bumble (Bombus griseocollis), Morrison bumble (Bombus morrisoni) Moths:Cycnia collaris Butterflies:Gray Hairstreak (Strymon melinus), Great Purple Hairstreak (Atlides halesus), Juniper Hairstreak (Callophrys gryneus), ⚠️Monarch butterfly (Danaus plexippus), Painted Lady (Vanessa cardui), Phyciodes picta, Pipevine Swallowtail (Battus philenor), Queen butterfly (Danaus gilippus), Western Pygmy Blue (Brephidium exilis)
Garden & Ecology Notes
- Wildlife Value:
- butterflies, bees, Monarch butterflies
- Deer Resistant:
- Yes
- Fragrant:
- Yes
- Fire Ecology:
- Fire adapted — tolerates or benefits from fire
- Fire Notes:
- Resprouts vigorously from root crown after fire or top removal. Common in fire-managed prairies and rangelands.
Soil Requirements
- Soil Type:
- sandy, well-drained, nutrient-poor soil
- pH:
- 6.0 - 8.0 (neutral to slightly alkaline)
- Drainage:
- excellent drainage required
- Moisture:
- dry to moderate
- Notes:
- Prefers open, sunny locations in arid regions
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–60 days
- Germination Time:
- 7–21 days
- Notes:
- Seeds germinate best with light exposure. Fresh seed may germinate without stratification but cold treatment improves uniformity.
The above propagation data sourced from Claude AI
Pre-treatment: Seed receives a 48 h soak in a stream of running water, followed by 10 weeks of cold moist stratification.
Establishment: The plant is commonly found in Central Western and Southwestern US states. There are variations in the pre-treatment protocols, with stratification periods ranging from none to 10 weeks.
Source: npn.rngr.net
ORGHPS Germination Guide: Should not need chilling