Milkweed Seed Pods

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Butterfly Gardening Botanical Identification

CREATING wildlife Habitats

FWBG, BRIT, Fort Worth, Texas Photograph

Jeanette Hyden

Green Milkweed, Antelope horn milkweed  (Asclepias viridis)

Green milkweed pods are usually erect, 2 ½ -5 in (6-13 cm) long and ½ – ¾ in (1-2 cm) wide. 

Milkweed is a host plant to the Monarch butterfly larvae.

FWBG, BRIT, Fort Worth, Texas

Photograph: Jeanette Hyden

Green Milkweed, Antelope horn milkweed  (Asclepias viridis)

A silky, hair-like structure assists in dispersing the seeds when the pods break open.  

BOTANICAL ILLUSTRATION, MILKWEED FRUITS AND SEEDS FROM PLANTS ILLUSTRATED.ORG

Asclepias species produce their seeds in pods termed follicles. The seeds, which are arranged in overlapping rows, bear a cluster of white, silky, filament-like hairs known as the coma (12) (often referred to by other names such as pappus, "floss", "plume", or "silk"). The follicles ripen and split open, and the seeds, each carried by its coma, are blown by the wind. Some, but not all, milkweeds also reproduce by clonal (or vegetative) reproduction. In botany, a follicle is a dry unilocular fruit formed from one carpel, containing two or more seeds. It is usually defined as dehiscing by a suture in order to release seeds.

floral morphology of plants in the genus Asclepias.Asclepias are often in clusters, with all of the flower stalks originating from a single point (an umbel).  The flowers are bisexual and actinomorphic (remember what that means from the Flower Symmetry  Each individual flower has a five-parted calyx (sepals) and a five-parted corolla (petals).  Pretty normal so far, but here’s where the flowers get interesting.  Each flower often has a corona (translated: crown) arising from the middle of the corolla.  The corona can look different on different species, but it often has five upright hoods that can be mistaken for petals.  Each hood often contains a pointed, incurved horn, also known as a crest or beak.  Surrounded by the five hoods is the gynostegium (2) which is a compound structure that includes the fused column of the stamens (male reproductive parts) and the heads of the styles (part of the female reproductive parts).  This is where the magic happens, folks.  The anthers (pollen-bearing portion of the stamens) are split into two halves, and each two adjacent half-anthers  connected at the corpusculum (a gland that assists in transporting pollen).  Unlike plants in most other genera, in which the pollen consists of individual grains or small groups of grains, the pollen in Asclepias is grouped into waxy masses known as pollinia (pollen sacs).  When an insect visits a milkweed flower for nectar (contained within the hoods), its legs slip into the crevices created by two adjacent half-anthers.  In the process, it unknowingly picks up a pair of pollinia that it takes to the next milkweed flower that it visits.  As its leg again slips into the crevice, it can distribute the pollinia if that crevice is vacant.  The pollinia need to be placed precisely into the crevice or pollination will not take place.

All material © 2021 by Jeanette Hyden for Grassroots Horticulture

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