Tucson Pollen Today and Tomorrow - November

Seasonal pollen has increased mainly due to weed growth promoted by the summer monsoon, but is expected to be less than usual because of this year's low rainfall.  Amaranthus palmeri (Carelessweed, one of the pigweeds) and  Salsola (Russian Thistle or Tumbleweed) have been flowering extensively throughout Tucson.   Ambrosia confertiflora (Slimleaf Bursage) is flowering.    Ambrosia ambrosiodes (canyon ragweed) and another ragweed,  Ambrosia deltoidea (triangle leaf bursage, rabbit bush) are also fully mature in the foothills but will not flower significantly until the spring.

Grasses have been flowering for several months.  Bermuda grass (Cynodon dactylon), established in alleys and roadsides, is drying up and unless irrigated will finish releasing pollen.  Other non-native grasses such as  Pennisetum ciliare (Buffel Grass) and native grasses such as Aristida (Threeawn) and Bouteloua (Grama Grass) have flowered extensively, and are now dormant.

Baccharis (Desert Broom) has been releasing pollen from the male flowers, and the tufted seeds maturing in the female flowers will fly in the wind in a few weeks' time.   Mold growth in the soil during the monsoon is yielding airborne spores now that the surface layers of soil are starting to dry up. 
 

Note:  This information is based on ongoing observation of flowering allergenic plants in the Tucson metropolitan area, and not on pollen counts.   Appearance and persistence of any particular airborne pollen species in the air usually lags behind the onset of flowering of the plant of origin.                                                                        Back

Updated 10-31-2009

Disclaimer:   This site is for educational purposes only.  Any information that you have found in this web site is not intended to replace medical care or advice given to you by your own physicians. You should consider consulting your local medical library and other web sites for additional information. 

Comments and suggestions welcome!   Email: schumach@u.arizona.edu
Content Owner:  Michael J. Schumacher, MB, FRACP, The University of Arizona