Asclepias verticillata

whorled milkweed, eastern whorled milkweed


Leaf Arrangement


Leaf Attachment


Leaf Type


Leaf Shape


Growth Form


Flower Color

green, white

Flower Month

May - September

Height (meters)

0.2 - 0.9

Milky Sap








Growing Season

Warm season

Prairie Coefficient of Conservatism


Field Characters

Narrow leaves and greenish-white flowers, whorled leaves, and its hoods are bent abruptly away from the anther. The pods are slender 1/2" in diameter and 3" long.

Cultural Information

Requires good drainage and full sun although it will tolerate some shade. It is easily propagated by seed and the seed requires no treatment. The pods split 4-6 weeks after flowering and the seeds should be kept in the pod until ripe. Fresh seed may be sown immediately. The germination of stored seed improves (unlike other Asclepias sp.) with cold/dry stratification (Steffen 1997). There are 68,800 seed/lb, and the recommended planting rate is 25 lbs/acre. Plants blooms in 1 year from seed. Stem cuttings can be taken during the growing season, dipped in rooting harmone, and rooted in sand or potting soil.

Animal Use

Larval host plant of monarch butterflies. Charles Robertson, 1928: (Insects suck nectar; most observations are from Robertson, otherwise they are from Betz, Moure & Hurd, and Hilty as indicated below) With pollinia: Bees (long-tongued) Apidae (Apinae): Apis mellifera fq; Apidae (Bombini): Bombus griseocallis fq, Bombus impatiens, Psithyrus citrinus; Anthophoridae (Ceratinini): Ceratina dupla dupla fq; Anthophoridae (Epeolini): Triepeolus lunatus concolor; Anthophoridae (Eucerini): Melissodes bimaculata bimaculata fq; Megachilidae (Coelioxini): Coelioxys octodentata; Megachilidae (Megachilini): Megachile brevis brevis fq; Megachilidae (Trypetini): Heriades variolosa variolosa Bees (short-tongued) Halictidae (Halictinae): Augochloropsis metallica metallica, Halictus confusus, Halictus rubicunda, Lasioglossum forbesii, Lasioglossum pilosus pilosus, Lasioglossum versatus; Halictidae (Sphecodini): Sphecodes dichroa, Sphecodes stygius; Colletidae (Hylaeinae): Hylaeus affinis Wasps Sphecidae (Astatinae): Astata unicolor; Sphecidae (Bembicinae): Bembix nubilipennis; Sphecidae (Crabroninae): Anacrabro ocellatus, Ectemnius rufifemur fq; Sphecidae (Larrinae): Tachytes aurulenta, Tachytes distinctus, Tachytes pepticus fq; Sphecidae (Philanthinae): Cerceris bicornuta, Cerceris clypeata fq, Cerceris compacta fq, Cerceris frontata, Cerceris rufopicta, Eucerceris fulvipes; Sphecidae (Sphecinae): Isodontia apicalis, Prionyx thomae, Sphex ichneumonea fq, Sphex pensylvanica fq; Vespidae: Polistes fuscata; Vespidae (Eumeninae): Eumenes fraterna, Euodynerus annulatus fq, Euodynerus foraminatus, Stenodynerus anormis; Tiphiidae: Myzinum quinquecincta fq; Scoliidae: Scolia bicincta; Pompilidae: Anoplius illinoensis, Anoplius lepidus, Cryptocheilus terminatus, Entypus fulvicornis, Poecilopompilus algidus Sawflies Argidae: Arge humeralis Flies Mydidae: Mydas clavatus; Syrphidae: Eristalis latifrons, Syritta pipiens, Tropidia quadrata; Conopidae: Physocephala texana, Physocephala tibialis; Tachinidae: Acroglossa hesperidarum, Archytas analis, Cylindromyia euchenor, Euclytia flava, Linnaemya comta, Ocyptera arcuatus; Sarcophagidae: Sphixapata trilineata fq; Muscidae: Neomyia cornicina; Calliphoridae: Cochliomyia macellaria, Phormia regina Butterflies Nymphalidae: Danaus plexippes Skippers Hesperiidae: Polites peckius, Staphylus hayhurstii Without pollinia: Bees (long-tongued) Apidae (Bombini): Bombus pensylvanica Bees (short-tongued) Halictidae (Halictinae): Agapostemon sericea, Lasioglossum albipennis, Lasioglossum imitatus; Halictidae (Sphecodini): Sphecodes cressonii Wasps Sphecidae (Crabroninae): Lestica confluentus, Oxybelus frontalis; Sphecidae (Philanthinae): Cerceris finitima; Sphecidae (Sphecinae): Ammophila nigricans, Prionyx atrata, Sceliphron caementaria; Sapygidae: Sapyga interrupta; Chrysididae: Holopyga ventrale Flies Syrphidae: Allograpta obliqua, Eristalis arbustorum, Eristalis transversus, Orthonevra nitida, Paragus bicolor, Sphaerophoria contiqua, Toxomerus marginatus, Toxomerus politus; Empidae: Empis clausa; Bombyliidae: Exoprosopa fasciata, Systoechus vulgaris; Conopidae: Physoconops brachyrrhinchus; Tachinidae: Copecrypta ruficauda, Gnadochaeta globosa, Gymnoclytia occidua, Paradidyma spinosula, Phasia purpurascens, Plagiomima spinosula, Senotainia rubriventris, Siphoplagia flaccidirostris, Trichopoda pennipes; Sarcophagidae: Gymnoprosopa polita, Sarcophaga sinuata; Calliphoridae: Helicobia rapax; Muscidae: Graphomya americana, Limnophora narona; Anthomyiidae: Calythea nigricans; Sepsidae: Sepsis violacea Butterflies Nymphalidae: Phyciodes tharos, Speyeria cybele, Vanessa atalanta; Lycaenidae: Everes comyntas; Lycaena hyllus; Pieridae: Colias philodice, Pieris rapae; Papilionidae: Papilio cresphontes Skippers Hesperiidae: Achalarus lyciades, Pholisora catyllus, Polites themistocles, Pompeius verna Moths Ctenuchidae: Cisseps fulvicollis Beetles Cerambycidae: Typocerus sinuatus; Rhipiphoridae: Macrosiagon limbata; Scarabaeidae (Cetonniae): Trichiotinus piger Plant Bugs Phymatidae: Phymata fasciatus prd Pollinia Presence Unspecified: Bees (long-tongued) Apidae (Apinae): Apis mellifera (Btz); Apidae (Bombinae): Bombus griseocallis (Btz); Megachilidae (Megachilini): Megachile latimanus (Btz) Bees (short-tongued) Halictidae (Halictinae): Lasioglossum pectoralis (MH); Colletidae (Colletinae): Colletes compactus (Btz) Wasps Sphecidae (Bembicinae): Bembix nubilipennis (Btz); Sphecidae (Larrinae): Tachytes aurulenta (Btz); Sphecidae (Sphecinae): Prionyx atrata (Btz), Sphex ichneumonea (Btz, H), Sphex pensylvanica (Btz); Tiphiidae: Myzinum quinquecincta (Btz); Vespidae: Polistes fuscata (Btz); Ichneumonidae: Ceratogastra ornata (Btz) Butterflies Nymphalidae: Junonia coenia (H), Vanessa cardui (H); Lyacenidae: Everes comyntas (H) Moths Sesiidae: Melittia cucurbitae (H) Beetles Cantharidae: Chauliognathus pennsylvanicus (H)

Natural History

Occurs in sandy and loamy soils with a pH of 6-7 and from mesic, dry mesic to dry. All aboveground parts are poisonous to livestock. Sheep are most affected. All milkweeds are called "herb 'a houatte" by Acadians and is thought to be a variation of "ouate" or "cotton wool". This name may refer to the use of its seed silk as down (Holmes 1990).


Dry, open woods, sandhills, rocky slopes, and roadsides.