Plants of allergenic importance in Northern Nevada

Alder (Alnus species)
Found in moist areas such as along streams and on lakeshores, alders in this area are slender trees with drooping pollen-bearing catkins about 3 inches long. Small cones, less than an inch long, emit winged seeds. They produce pollen in March through May, before their leaves appear.

Alfalfa (Medicago Sativa)
A member of the legume family grown for horse and cattle fodder. We see many people with positive allergy skin tests to alfalfa, particularly those living in farm and ranch areas. Since it is perennial crop, there is no specific season of pollination. Wild alfalfa, common along roadsides, pollinates in mid-summer.

Arizona cypress (Cupressus arizonica)
A medium-size tree, the only cypress native to the Southwest. It is found on dry mountain slopes and canyon walls but can also do well when planted as a drought-tolerant ornamental and is used for windbreaks and erosion control. Pollinates in March and April.

Ash (Fraxinus species)
Members of the olive family, ash trees are not native to this area, but are used in landscaping. Their flowers appear before their leaves, and we find their pollen in March, April and May. By the way, the popular mountain ash tree is not related--it belongs to the rose family and is not an allergenic plant.

Aspen (Populus species)
Known for their brilliant yellow color in the fall at higher altitudes and their trembling leaves, the quaking aspen has drooping catkins up to 4 inches long. Closely related to cottonwoods and poplars, it is an early springtime pollinator.

Birch (Betula species)
Often graceful, birches pollinate in springtime. Abundant birch pollen in the Reno area is responsible for "nose woes" and other allergy symptoms from March through May.

Box elder (Acer negundo)
A close relative of the maples, this fast-growing tree common in the Midwest is sometimes used as a landscaping ornamental in this area. Largest amount of pollen dispersed in May.

Burning bush (Kochia scoparia)
This multi-branched compact weed that grows to about three feet high has aliases including Mexican fireweed and fireball. It turns a brilliant red in the fall and has been used as an ornamental hedge. Pollinates in late summer through fall.

Cocklebur (Xanthium species)
A member of the ragweed family, cocklebur is a coarse weed found in pastures, irrigation ditches, and marshy areas. Like the other weeds, highest pollen levels are in late summer and fall.

Clover (Melilotus species)
Clover, alfalfa, and broom are leguminous plants that cross-react allergenically, causing allergy symptoms when their pollen levels peak in the spring and summer. Sorry, but if you are one of the many people who are repulsed by broom's audacious odor, it's going to be just as sickeningly sweet after we fix your allergies.

Cottonwood (Populus species)
These trees' "cotton" that fills the air in springtime actually causes less trouble than its invisible allergy-inducing pollen, which is prevalent in northern Nevada in March, April, and May.

Curly dock (Rumex crispus)
This slender weed, a member of the buckwheat family, is commonly seen in cultivated fields, along roadsides, and in ditchbanks. It grows to about four feet high and has crowds of small, dull yellow flowers. It pollinates from late spring through summer in this area.

Elm (Ulmus species)
Not native to the West, but commonly planted as a shade tree, elms are subject to pests and diseases, including a fungus known as Dutch elm disease, making them messy. Elms and junipers lead off our hay fever season, putting out troublesome pollen beginning in February.

Grasses (Gramineae family)
Widespread native and cultivated grasses are summertime pollinators that mostly cross-react allergenically, thus if you are allergic to one you are probably allergic to all grasses. If you have to cut the lawn, wear a "dust and pollen mask". Hay fever and asthma symptoms can also be due to fungal spores whipped into the air by the mower.

Juniper (Juniperus species)
Widespread shrubs and trees occurring both naturally and as a hardy landscape plantings. Their potent pollen, so plentiful that it appears as smoke if you strike a branch, is abundant in northern Nevada from February into June, and is responsible for many allergy symptoms.

Linden (Tilia species)
Interestingly, the linden does not seem to be as allergenic in this country as it is in Europe. This may be due to the fact that it is more insect-pollinated here and more wind-pollinated in Europe. As with trees in general, linden pollinates in springtime.

Locust (Robinia species)
This is a drought-resistant eastern tree planted in the West along roadsides and on hillsides for erosion control. It adapts well to dry, hot conditions and will thrive in poor soil. A springtime pollinator.

Maple (Acer species)
Attractive landscape trees that contribute to many people's nasal, sinus, eye, ear, and lung symptoms in our area in the springtime. The good news: even if you're allergic to maple's pollen, you can probably enjoy maple syrup without problems. We find maple pollen in northern Nevada from March through June, peaking in May.

Mulberry (Morus alba)
Fruitless varieties are prodigious springtime pollen producers that tolerate heat and alkaline soil. The paper mulberry was originally planted in the South to develop a silkworm industry. Two wonderful specimens with large rose-lavender flowers in late spring and early summer can be seen at the north end of Virginia Lake.

Oak (Quercus species)
Pin oak has become a popular landscape tree in our community. Its clean good looks and tenacious leaves are appreciated by many, but its allergy-causing pollen by few. A late spring pollinator.

Pigweed (Amaranthus family)
Plants of the pigweed (Amaranthus) and goosefoot (Chenopodium) families grow aggressively in cultivated or otherwise disturbed soil. Names of some, like "rough redroot pigweed," aptly describe them. Their abundant pollens are responsible for a variety of airway symptoms during late summer and into autumn.

Pine (Pinus species)
Although pines are widespread and their waxy, yellow pollen is notorious for coating windshields and forming a scum on water, allergy skin testing often reveals that symptoms during the many months of pine pollination are actually due to other plants that pollinate at the same time. Its extensive pollination period in our area lasts from March into late fall.

Plantain (Plantago species)
Common weeds in lawns, meadows, and waste lands. Less than a foot tall, English plantain (Plantago lanceolata) survives heavy traffic. Heaviest pollination is during summertime. Psyllium seed from a related plant is used as a laxative and can produce adverse symptoms in patients allergic to plantain.

Poplar (Populus species)
The lombardy poplar is a rapidly growing columnar tree native to Italy that is used to good decorative advantage along driveways and as a windbreak. It does well in cold, dry climates. Pollinates March through May in our area.

Privet (Ligustrum species)
A member of the olive family, privet is mostly used as an evergreen hedge. The flowers draw bees (which can be minimized by clipping the hedges, eliminating most of the flower-bearing branches). Some people find the fragrance annoying. A spring pollinator.

Rabbitbrush (Chrysothamnus naseosum)
This first cousin to ragweed is golden yellow in the summer and fall. Handsome for a high desert weed, its scientific name tells you how much its allergy-causing properties are admired! Pollinates summer into early autumn.

Ragweed (Ambrosia species)
Despite a scientific name that means food of the gods, North America's 17 species of ragweed don't have many friends. Much more of a problem east of the Mississippi--where giant ragweed (Ambrosia trifida) can grow to 12 feet--than in our area, different species of ragweed can found in all states and some can put out pollen when only inches in height. Typically pollinates mid-summer into September.

Russian olive (Elaeagnus angustifolia)
Rapidly growing tough little trees with thorny dark branches that tolerate heat and wind and need little attention. Small greenish-yellow flowers give rise to fruit that look like small olives. The silverberry (E. commutata) is a close cousin. Springtime pollinators.

Russian thistle (Salsola kali)
More commonly known as "tumbleweed," this and sagebrush are hallmarks of the western deserts. If you've got allergy problems in the fall and you're not allergic to tumbleweed you're not from the West. 'Nuff said?

Sagebrush (Artemisia species)
Nevada's state flower, it pollinates in summer through late autumn and causes chukar hunters as well as home bodies to sneeze, wheeze, and rub their eyes. A plume of greenish flowers the same color as the leaves grows out of the top of each stem.

Salt cedar/Tamarisk (Tamarix ramosissima)
A small tree introduced into the Southwest in the early 20th century, it does well along water courses, where it is often found growing with cottonwoods. Pollinates March through August.

Sycamore (Platanus species)
The "plane tree" is popular as an ornamental. It has leaves that look like enormous maple leaves and golf ball-sized green fruits that turn yellow-brown as they mature. Pollinates springtime into early summer.

Willow (Salix species)
Although Salix gave us acytl-SALI-cylic acid, or aspirin, this attractive native with catkins that turn fuzzy and spread seeds in the wind and its pretty cultivated cousins can be just one more headache for the allergy sufferer. Pollinates in the spring.

Miscellaneous desert plants
The following shrubs might add to allergy problems in our area but we have insufficient data to be certain of their allergenic importance:

Bitterbrush, deerbrush, horsebrush
Shrubs in sagebrush deserts usually about twice the size of sagebrush. Small yellow flowers appear for about two weeks in June or July, depending on temperature and precipitation.

Desert peach
A pretty shrub of the rose family. Pink flowers precede little pink and green fruits that look like tiny peaches. Being insect pollinated, it is probably not responsible for many allergy problems.

Ephedra ("Mormon tea")
Looks like broom. Clusters of small golden-yellow flowers at the ends of stems.