Helianthus nuttallii


Tall Sunflower

Upper Quarter of Plant

Moosomin Regional Park
21-August-2004

The keys to the species in both Flora of Alberta and Budd's Flora state that the leaves of H. nuttallii are lanceolate or linear-lanceolate.  However, Flora of Canada identifies ssp. rydbergii as having the larger basal leaves mostly not over twice as long as broad.  The herbarium specimens of this variety have leaves tending to ovate-elliptical.

Budd's Flora identifies var. subtuberosus as having lanceolate to linear-lanceolate leaves, compared to lanceolate leaves for the type.  However, Flora of Canada includes species H. subtuberosus in ssp. rydbergii.

In any case, the leaves of this species appear to be variable in shape.  However, the leaves are NEVER folded lengthwise, which distinguishes this species from H. maximilianii.

Nuttallii:  Answers to key questions in Budd's Flora and Flora of Alberta leading to this species.  

perennials

rootstocks NOT tuber-bearing

stem glabrous or somewhat scabrous below the inflorescence, sometimes glaucous; NOT conspicuously pubescent below the inflorescence with short white hairs

leaves mostly opposite; NOT alternate

leaf blades generally lanceolate or linear-lanceolate; NOT ovate; NOT somewhat rhombic

leaves NOT folded lengthwise

leaves rough above but somewhat hairy beneath; NOT rough on both sides

involucre bracts narrow, mostly with loose acuminate tips; NOT broad, NOT firm, NOT appressed

involucre bracts usually scabrous and conspicuously hairy on the margins; NOT covered with short white hairs, sometimes ciliate towards the base

receptacle convex or low-conical; NOT flat  or nearly so

disk of flower heads yellow or light brown; NOT purple, NOT red, NOT dark brown

 

Helianthus: Answers to key questions in Budd's Flora and Flora of Alberta leading to this genus. 

perennial

plants NOT with a woody caudex

juice watery; NOT milky

plants NOT heavy scented

plants more or less leafy-stemmed (although leaves may be confined to the lower part of the stem); NOT scapose or scapiform; NOT with cauline leaves none; NOT with cauline leaves few and reduced to mere bracts

leaves NOT compound

at least the lower leaves opposite; leaves NOT all alternate

involucre NOT glandular-glutinous

involucre bracts in one or more series, but all of the same nature; NOT in 2 distinct, dissimilar series

receptacle flat or convex; NOT conic, NOT cylindrical; NOT columnar; NOT tall

receptacle with chaffy scales between the florets; NOT merely bristly; NOT naked

flower heads with both tubular and ray florets

ligulate (ray) flowers either pistillate or neutral

rays conspicuous; NOT inconspicuous

ray florets yellow

stamens united to form a tube around the pistil

pappus of small scales or awns, soon falling off; NOT composed of hairs; NOT absent; NOT present merely as a short crown

pappus awns NOT barbed