Species: Helianthus tuberosus L.

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Helianthus tuberosus L.

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TAXONOMY

Family:

Asteraceae or Compositae

Genus:

Helianthus

Species Synonyms:

Helianthus tomentosus Michx.
Helianthus tuberosus var. subcanescens Gray

Common Names:

Jerusalem artichoke
Jerusalem sunflower

DISTRIBUTION

Canada:

southeastern Saskatchewan – Ontario

Saskatchewan:

southeastern Saskatchewan; Souris River Valley and Antler River Valley

Ecoregion:

Moist Mixed Grassland, Aspen Parkland

HABITAT

Saskatchewan:

semi-shaded or wooded river shores

Associated Species:

chokecherry, earlyleaf brome, field sowthistle, fragrant bedstraw, Manitoba maple, marsh hedgenettle, purple meadowrue, smooth brome, Virginia wild rye

RARITY STATUS

Provincial Status According
to Harms (2003):

Threatened

Nature Conservancy Status:

G5 S2

Saskatchewan Species at
Risk Status:

None

COSEWIC Status:

None

Jerusalem artichoke is highly regionally restricted in the province, occurring only in the southeast corner. These populations represent the northern and western expansion of this species.

SPECIES DESCRIPTION

Height:

1 – 3 m tall

Roots:

fibrous; cigar-shaped, semi-edible tubers on rhizomes

Stems:

thick, firm, branched above, rough hairy, occasionally hairless

Leaves:

opposite, uppermost alternate, abruptly tapered at base to leaf stalk, 10 – 25 cm long, 6 – 15 cm wide, oval to broadly lance-shaped, 3-nerved for at least half of blade length, veins yellow on underside of leaf, upper surface rough hairy, lower surface minutely hairy, margin saw-toothed

Inflorescence:

heads several, 1 – 2.5 cm broad; stalks rough-hairy; bracts in 3 series, equal to or slightly exceeding disc, loose or reflexed at maturity, lance-shaped, tip tapered; receptacle low convex, dry bracts on receptacle hairy at tip

Flowers:

ray flowers 5 – 15, 2 – 4 cm long, to 1 cm wide, 3 teeth at tip, female, infertile, yellow; disc flowers numerous, perfect, fertile, yellow

Fruits:

achenes 5 – 7 mm long, hairless; pappus two deciduous awns

*KEY TO HELIANTHUS* SPECIES IN SASKATCHEWAN**

1 Annuals; taproots; leaves mostly alternate; receptacle flat or nearly so	2
1 Perennials; tough creeping rhizomes or erect branching crowns; leaves mostly opposite (upper leaves commonly alternate); receptacle convex or low conical	3

2 Lower leaves heart-shaped and toothed, hairs rough; bracts gradually tapered with conspicuously hairy margins; central bracts on receptacle not very hairy	H. annuus
2 Lower leaves not heart-shaped, entire; bracts gradually tapered and not conspicuously hairy; central dry bracts with white hairs at tip	H. petiolaris ssp. petiolaris

3 Disc flowers dark brown, purple, or red	4
3 Disc flowers yellow or brown	5

4 Plants 1 – 2 m tall; leaves in 7 or more pairs; blade oval to inversely lance-shaped, 8 – 20 cm long, tip long-tapered	H. pauciflorus ssp. pauciflorus
4 Plants < 1.2 m tall; leaves in 5 – 7 pairs; blade rhombic to lance-shaped, 5 – 12 cm long, tip tapered to obtuse	H. pauciflorus ssp. subrhomboideus

5 Bracts appressed to the disk, overlapping	H. pauciflorus ssp. pauciflorus
5 Bracts loose-spreading, all about the same length	6

6 Rootstocks with tubers; leaves oval to broadly lance-shaped, generally 3 times as long as wide	H. tuberosus
6 No tubers; leaves lance-shaped to linear, generally at least 3 times as long as wide	7

7 Middle leaves may be folded lengthwise, rough-hairy above, occasionally below	H. maximiliani
7 Middle leaves always flat, rough-hairy to woolly above, rough-hairy to long-woolly below	8

8 Stems 20 – 30 dm tall; upper leaves alternate, lance-shaped and tapered to the tip	H. nuttallii ssp. nuttalli
8 Stems 5 – 20 dm tall; upper leaves mostly opposite, lance-shaped to oval, tip tapered to obtuse	H. nuttallii ssp. rydbergii