CoIhOrado We:ed Seeds 
77 
6. Sunffower, Ground Artichoke 
(Helianthus L.) 
Achenes obscurely 4-angled, flattened or compressed, thick, oblong, or 
short wedge-shaped ; pappus of 2 scales or awns, seldom persisting at maturity. 
Key to Species 
Seeds usually smooth, striped 1..H. annuus 
Seeds usually hairy, mottled 2..H. petiolaris 
1. Common Sunt'lower {Helianthua 
annuus L,, Helianthus lenticularis Dougl.) 
(Fig. 149). — Seeds pale smoke-gray to drab- 
gray in color, mottled with broken, black 
lines or spots, smooth or hairy, the hairs 
more pronounced near the top ; seeds 4-6 mm. 
long, 2.5-3 mm. wide, straight, mostly ovate 
to wedge-shaped. 
Fig. 149. Com- 
mon Sunflower 
(Helianthus an- 
nuus). X 6. 
2. Prairie Sunflower {Helian- 
thus petiolaris ~Sutt.).. (Fig. 150). — 
Seeds wood-brown to buffy-brown in 
color, mottled though not as in H. 
annuus, but usually more hairy ; 
achenes 4-6 mm. long, 2-2.5 mm. wide, 
straight, mostly ovate to wedge-shaped. 
7. Gum Plant, Resin-weed, Tar-weed 
{Orindelia Willd.) 
Achenes short, thick, (ending abruptly 
as though cut off transversely) 4-5 ribbed, 
flattened, smooth; pappus of 2-S awns or 
bristles which fall off at maturity; achenes 
honey-yellow to chamois in color. 
Gum Plant {G-rindelia sp.) (Fig. 151). — ■ 
In Colorado alone there are eleven known 
species^ of Gum Plant. 
The seeds of the several species have 
many characters in common. Up to the 
present time the seeds of these species have 
not been differentiated systematically. 
Flora of Colorado — Rydberg. 
Fig. 151. Gum Plant (Grin- 
delia sp.). x 11. 
Fig. 150. Prairie 
Sunflower (Helian- 
thus petiolaris). x 11. 
