Arizona Sunflower
Tithonia thurberi
Found in partial shade on a sandy terrace alongside Madera Canyon, Sta. Rita Mts., Arizona, USA. 10 September 2010.
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ANNUAL:
Herbaceous annual which may germinate after spring or summer rains. At flowering, plants
typically are about 100 cm tall. Branches freely
above base of plant yielding a plant half again wide as tall.
FLOWERS: The disc florets are more yellow than Helianthus annuas and the rays
are fewer and shorter. Blooming after summer rains, August and September.
LEAVES: Leaves are broadly elyptic/triangular and tapering to tip and base. Margins are
round-toothed.
RANGE: Fairly common in the sycamore canyons close to the Arizona-Mexico border.
FRUIT: Each ray and disc flower tops a large seed. Dry single-seeded achene topped by less than a
dozen fine bristles.
UNARMED. Without thorns.
The flowers are attractive to a wide variety of insects such as flower buprestids.
Asteraceae -- Sunflower Family
More Information:
- Southwest Environmental Information Network
- Encyclopedia of Life
- USDA Plant Profile
- Google Images
- Google Scholar Literature Search