Siam weed (Chromolaena odorata) is in the Sunflowers, Daisies, Asters, and Allies family (Asteraceae). Across the U.S., iNaturalist users have logged 968 research-grade flowering observations of it in our sample, peaking in November.
Nationally it blooms mainly from October to January, but timing varies a lot by state and elevation — see the table below.
When to photograph Siam weed: observations by month (U.S.)
About Siam weed
Chromolaena odorata is a tropical and subtropical species of flowering shrub in the sunflower family. It is native to the Americas, from Florida and Texas in the United States south through Mexico and the Caribbean to South America. It has been introduced to tropical Asia, west Africa, and parts of Australia. Common names include Siam weed, Christmas bush, devil weed, camfhur grass, common floss flower and triffid.From Wikipedia via iNaturalist — article, CC BY-SA.
Siam weed by state
| State | Observations | Peak month | Main season |
|---|---|---|---|
| Texas | 874 | November | Oct–Dec |
| Florida | 92 | December | Dec–Jan |
Main season = months with at least 30% of the state's peak-month count.
Related wildflowers (Sunflowers, Daisies, Asters, and Allies)
black-eyed Susan
Common Yarrow
White Snakeroot
Chicory
Lawn daisy
Philadelphia fleabane
Pearly Everlasting
Blue Mistflower
Photography tips
- Photograph flowers on calm, overcast mornings to avoid wind blur and harsh shadows.
- Get low: a shallow depth of field (f/2.8–f/5.6) isolates a bloom against soft color.
- Stay on trails — trampling meadows kills plants and ruins next year's display.
- Try a kaleidoscope abstract of a single bloom with our online kaleidoscope tool.
FAQ
When is the best time to photograph Siam weed?
Nationally, November has the most observations, with the main season from October to January.
Where is Siam weed most often seen?
The most observations come from Texas, Florida.