Species: Myriophyllum pinnatum (Walt.) B.S.P.

comments | credits | copyright

Back to: Plants at Risk in Saskatchewan

Myriophyllum pinnatum (Walt.) B.S.P.

Species Image Gallery
(opens in a new window)

TAXONOMY

Family:

Haloragaceae

Genus:

Myriophyllum

Species Synonyms:

Myriophyllum scabratum Michx.
Potamogeton pinnatum Walt.
Myriophyllum verticillatum var. cheneyi Fassett

Common Names:

cutleaf watermilfoil
green parrot’s feather
pinnate water-milfoil

DISTRIBUTION

Canada:

southeastern Saskatchewan, southwestern Ontario

Saskatchewan:

southeastern Saskatchewan

Ecoregion:

Moist Mixed Grassland

HABITAT

Saskatchewan:

shallow sloughs

RARITY STATUS

Provincial Status According
to Harms (2003):

Endangered/Extirpated?

Nature Conservancy Status:

G5 S1

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Cutleaf watermilfoil is endangered or possibly even extirpated from Saskatchewan. This plant is extremely rare and is known only from one location and its existence in the province has not been verified for at least 50 years.

SPECIES DESCRIPTION

Height:

rhizomes

Stems:

perennial, aquatic, 30 – 150 cm long, branches simple to spreading

Leaves:

underwater leaves whorled in groups of 3 – 6, 0.7 – 3.0 cm long, limp, with 3 – 5 pairs of thread-like divisions; above water leaves linear and narrow, longer than flowers, upper leaves rigid, irregularly lobed to shallowly toothed

Inflorescence:

spikes above water, axillary, 10 - 20 cm long, 4 – 6-flowered; male flowers above, female below; lowermost bracts grading into leaves

Flowers:

flowers perfect or unisexual; sepals 4, purplish, petals 4, purplish; stamens 4; ovary inferior

Fruits:

nut-like, deeply 4-lobed, nearly round, pale

MYRIOPHYLLUM KEY FOR SPECIES FOUND IN SASKATCHEWAN

1 Flowers in axils of leaves below or above water; stamens 4	M. pinnatum
1 Flowers in a terminal spike; stamens 8	2

2 Floral bracts alternate; under water leaves with up to 7 pairs of thread-like divisions	M. alterniflorum
2 Floral bracts opposite or whorled; under water leaves with up to 11 pairs of thread-like divisions	3

3 Above water leaves reduced, bract-like, upper leaves entire, lower saw-toothed; leaf whorls greater than or equal to 1 cm apart	M. sibiricum
3 Above water leaves pinnately lobed, margins comb-like, saw-toothed or entire; leaf whorls less than 1 cm apart	4

4 Floral bracts shorter than or equal to fruits, margin saw-toothed to entire	M. verticillatum
4 Floral bracts usually surpassing the fruits, margin saw-toothed to comb-like	M. spicatum