Ontario Weeds: Clasping-leaved dogbane
Table of Contents
- Name
- Other Names
- Family
- General Description
- Stems and Roots
- Leaves
- Flowers and Fruit
- Habitat
- Similar Species
- Caution
- Related Links
Name: Clasping-leaved dogbane Apocynum
sibiricum Jacq.,
Other Names: apocyn a feuilles embrassantes,
Indian hemp, Prairie dogbane, chanvre sauvage
Family: Dogbane Family (Apocynaceae)
General Description: Resembles both
Spreading
dogbane and Indian hemp and before flowering is easily confused
with Common
milkweed. Perennial from deeply penetrating and widely spreading
coarse roots, these often 20-30cm (8-12in.) below the surface.
Photos and Pictures
Clasping-leaved dogbane, showing deep perennial root
from which 4 shoots emerged.
Clasping leaved dogbane. C. 3 shoots forma
deep, coarse perennial root (dotted line represents ground surface),
and leaves on lower portion of 1 shoot.
Stems & Roots: Stems coarse, erect,
up to 1m (40in.) tall, arising from buds on the roots; the main stem
with branches throughout its length, smooth and hairless, green or
with a slight pinkish cast.
Leaves: Leaves usually opposite but occasionally
alternate, mostly sessile or with very short petioles (usually not
more than 3-5mm, 1/8-1/5in. long), up to 5cm (2in.) wide and 12cm
(4¾in.) long or sometimes larger, oblong to broadly elliptic
with a somewhat abruptly pointed tip and a broadly rounded to heart-shaped
base, smooth and hairless on both surfaces, the undersurface lighter
green than the upper; the basal lobes of the larger leaves somewhat
clasping the stem.
Flowers and Fruit: Inflorescence, flowers
and seedpods similar to those of Spreading dogbane except that the
calyx lobes of Clasping-leaved dogbane are narrow and 3-5 times longer
than wide, and its corolla is white and usually only 3-6mm (1/8-¼in.)
long. All parts of the plant contain milky juice. Flowers from July
to September.
Habitat: Clasping-leaved dogbane is
also a native plant with much the same distribution and abundance
as Spreading dogbane
Similar Species: It is distinguished from
both Spreading dogbane and Indian hemp by the lower leaves on its main
stem and lower branches having heart-shaped bases that more or less
clasp the stem, and the petioles of all leaves being very short or almost
absent; and, from Spreading dogbane by the undersides of its leaves
being virtually hairless, even along the midribs, as well as by its
smaller white flowers having very narrow sepals. It is distinguished
from Common milkweed by its lighter green leaves having abruptly pointed
tips and being virtually hairless (those of milkweed being somewhat
bluish-green, more rounded at the tip, and finely velvety hairy on the
undersurface); by its loosely branching inflorescence (not an umbel)
with small white flowers, and by its pencil-thin seedpods.
Caution: May be poisonous to livestock.
Related Links
... on general Weed
topics
... on weed identification, order OMAFRA Publication 505: Ontario Weeds
... on weed control, order OMAFRA Publication 75: Guide To Weed Control
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