Swamp Milkweed

swamp milkweed
milkweed

More info for the terms: caudex, rootstock

Swamp milkweed is an erect plant, 11 to 18 inches (0.3-0.5 m) tall, with
milky sap. It has a short rootstock or caudex with shallow fibrous
roots. A plant may have one to several leafy stems. Its lance-shaped,
opposite leaves have short stalks. Flowers have many elaborate
structures (e.g., hoods and horns) and are arranged in flesh-colored
terminal umbels [23].

More info for the term: swamp

Swamp milkweed is found throughout the eastern and midwestern United
States and Canada. It occurs from Prince Edward Island and Maine west
to southern Manitoba [20,23,21]. Swamp milkweed continues southeast
through the Midwest and Great Plains to Florida [6,15,18]. Its
distribution extends westward to Texas and New Mexico [2,20,24]. Six
disjunct areas of its range occur in southern Idaho, Wyoming, Nevada,
and north, central, and south Utah [3,26].

More info for the terms: fire regime, seed, severity, swamp

The moist habitat of swamp milkweed discourages fire entry. Swamp
milkweed is very shallowly rooted; it would most likely be killed in a
fire of any severity. Adjacent communities may serve as seed sources
after a fire. Swamp milkweed is a component of prairie wetlands, so it
has evolved with some fire exposure.

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".

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More info for the term: hemicryptophyte

Hemicryptophyte

Swamp milkweed is a semiaquatic plant [3]. It occurs in a range of wet
conditions from standing water to saturated soil. A riparian species,
it is found on streambanks, pond shores, banks, and floodplains of
lakes, waterways, marshes, swamps, and wet areas of prairies
[6,13,18,21]. Additionally, it occurs in wet meadows and in low wet
woods [23].

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This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

More info for the term: swamp

45 Pitch pine
50 Black locust
53 White oak
55 Northern red oak
57 Yellow-poplar
58 Yellow-poplar - eastern hemlock
59 Yellow-poplar - white oak - northern red oak
61 River birch - sycamore
64 Sassafras - persimmon
65 Pin oak - sweetgum
69 Sand pine
70 Longleaf pine
73 Southern redcedar
75 Shortleaf pine
79 Virginia pine
80 Loblolly pine - shortleaf pine
81 Loblolly pine - shortleaf pine
83 Longleaf pine - slash pine
84 Slash pine
87 Sweet gum - yellow-poplar
88 Willow oak - water oak - diamondleaf oak
89 Live oak
91 Swamp chestnut oak - cherrybark oak
96 Overcup oak - water hickory
97 Atlantic white cedar
101 Baldcypress
102 Baldcypress - tupelo
103 Water tupelo - swamp tupelo
104 Sweetbay - swamp tupelo - redbay
105 Tropical hardwoods
109 Hawthorn
110 Black oak
111 South Florida slash pine
222 Black cottonwood - willow
235 Cottonwood - willow
252 Paper birch

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This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES12 Longleaf - slash pine
FRES13 Loblolly - shortleaf pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
FRES28 Western hardwoods

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This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

K025 Alder - ash forest
K081 Oak savanna
K082 Mosaic of K074 and K100
K084 Cross Timbers
K089 Black Belt
K090 Live oak - sea oats
K091 Cypress savanna
K100 Oak - hickory forest
K104 Appalachian oak forest
K105 Mangrove
K110 Northeastern oak - pine forest
K111 Oak - hickory - pine forest
K112 Southern mixed forest
K113 Southern floodplain forest
K114 Pocosin
K115 Sand pine scrub
K116 Subtropical pine forest

More info for the terms: caudex, fire severity, seed, severity, swamp

No fire studies on this plant have been reported. A fire would kill
swamp milkweed back to the caudex. In moist soil, the caudex is usually
not deeply rooted. Death would depend upon fire severity. It may
survive a cool fire. Late season (summer and fall) fires would have the
greatest effect on this species. Since its seeds are not shed until
October or November, a late season fire would kill the seed crop of the
current year.

More info for the term: swamp

Swamp milkweed foliage and stems have been reported to cause mortality
in sheep. It is not known why sheep are so susceptible [7,12].
Muskrats are unaffected by swamp milkweed and readily eat the roots
[23].

More info for the term: forb

Forb

AZ CT FL GA ID IL IN LA ME MA
MI MN MO NV NH NM ND OK RI SC
SD TN TX UT VT VA WI WY MB NB
NS ON PE PQ

More info for the term: seed

Swamp milkweed seeds have long hairs, called comas. Seed comas have
been used as pillow and lifejacket stuffing [3,23]. Stem fibers have
been suggested as substitutes for flax and hemp [3]. Young shoots,
inflorescences, and leaves may be cooked with several changes of water
and eaten [23]. This plant causes dermititis.

Milkweeds in general are not palatable to wildlife. The bitter milky
juice is high in alkaloids [17]. Most animals avoid it unless forced to
eat it on overgrazed pastures [17].

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More info for the term: swamp

Across its range, swamp milkweed begins to flower during the last week
of June or the first week in July and continues until August or
September [2,6,15,18,21,23]. Individual flowers remain open for about 1
week [9]. Fruits mature from August through October [2,6,15,18,21,23].
After maturation, follicles split open on one side to release seeds
during October and November [23].

More info for the terms: caudex, fruit, seed, severity, surface fire, swamp

Following a cool surface fire, swamp milkweed sprouts from the caudex
and produces fruit. If plants have been killed, off-site seeds will be
wind dispersed into the burned area. This seed will germinate on burned
areas during the first postfire growing season, provided soil conditions
are wet.

Long-term response: Swamp milkweed should have no difficulties in
maintaining populations. It can self-fertilize; sexual reproduction
will continue, despite a reduced number of colonizing plants.

Plant recovery is controlled by the severity of the fire and
availability of adequately wet habitat.

More info for the terms: caudex, root crown, seed

survivor species; on-site surviving root crown or caudex
off-site colonizer; seed carried by wind; postfire years 1 and 2

More info for the terms: caudex, rootstock, seed, stratification, swamp

Swamp milkweed readily germinates from seed shed the previous year (50
to 88 percent germination [11]) after cold stratification, 39 degrees
Fahrenheit (4 deg C), for approximately 9 months. A plant puts up an
average of one stem from a short caudex and sprouts each year from this
rootstock. Flowers are insect pollinated (Hymenoptera and Lepidoptera)
[10]. Seeds have long hairs that facilitate wind dispersal in the fall.
Swamp milkweed is self-fertile [8]. It very rarely reproduces asexually
by rhizomes [8].

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This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

6 Upper Basin and Range
8 Northern Rocky Mountains
10 Wyoming Basin
11 Southern Rocky Mountains
12 Colorado Plateau
13 Rocky Mountain Piedmont
14 Great Plains

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Swamp milkweed is a colonizer. It has wind-dispersed seeds and can
self-fertilize.

Asclepias pulchra Ehrh. ex Willd.

More info for the term: swamp

The currently accepted scientific name of swamp milkweed is Asclepias incarnata L.
(Asclepidaceae). There is disagreement in the taxonomic literature
about infrataxa treatment. Two subspecies are recognized:

Asclepias incarnata ssp. incarnata [23]
A. i. ssp. pulchra (Ehrh. ex Willd.) Woods. [23]

Also recognized are the following variety and forms:

A. i. var. incarnata f. incarnata [21]
A. i. var. incarnata f. albiflora--Found only in Missouri [21]
A. i. var. incarnata f. rosea Bowin--Found only in southern
Ontario, Canada [18].

This report does not use infrataxa; they rarely appear in the
literature.

More info for the term: seed

Swamp milkweed is currently used in Wisconsin for wetland rehabilitation
[11]. It is included in commercially available seed mixes.