Pinus sp. & the Family Pinaceae
Pines and Related Conifers
By: H. Wayne Shew, Ph.D.
NAB Certified Pollen Counter
Alabama Allergy & Asthma Center Collection Station—Birmingham, Alabama
Pinus sp. & the Family Pinaceae – Pines and Related Conifers
(Trees Producing Pollen Described as Having Micky Mouse Ears)
It is probably a safe statement to say that a large majority of adults in the Southern U.S. can readily distinguish pines from other types of trees. Pines and members of the Pinaceae family of plants produce leaves that are needle-like in shape, and seed producing structures called cones. However, not everyone will readily recognize the different species of pines native to Alabama and the Southeastern United States.
Pines belong to the genus, Pinus which is a member of the family of plants called Pinaceae. There are nine genera in the Pinaceae family worldwide, but only six are found in North America: Pinus (pine), Pseudotsuga (Douglas fir), Abies (fir), Picea (spruce), Larix (larch), and Tsuga (hemlock). Of these genera, only Pinus, and Tsuga are found in our area of the Southeast, that is Alabama, and only pines are present in any significant number throughout the state. There are seven species of pines native to Alabama with four of these species found in the northern half of the state.
Pines are found in all types of habitats throughout the state, from moist, poorly drained floodplains to drier upland slopes and dry rocky soils. Pines readily invade abandoned fields and waste places and rapidly form pure stands in such areas. They are one of the dominant and obvious stages in the process called secondary plant succession. The predominant species of pine in our area is loblolly, Pinus taeda. There are also numerous Virginia pines, P. virginiana, in some locations. Virginia pines are also called scrub pines and are commonly found on dry upland sites throughout northern Alabama. The coastal plain region often has scattered stands of long leaf pines, P. palustris, in addition to loblolly and Virginia pine. Long leaf pines had a much more extensive range in Alabama historically, but because of logging activities and fire suppression, regrowth of long leaf pine forests all but disappeared. Now, much of the area formerly dominated by long leaf pine trees is dominated by loblolly pines. Short leaf pines, P. echinata, also were once present in large numbers in northern Alabama, both in pure and mixed stands. Short leaf pine acreage has dropped significantly in recent times and when harvested is seldom replanted; preference being given to replanting using loblolly pine seedlings.
Most genera in the family Pinaceae produce pollen that is best described as having “Micky Mouse ears.” These genera include Abies, Picea, and Pinus. The pollen grains produced by these genera have two air bladders that extend out from the sides of the basically circular pollen grain giving it the appearance of a Micky Mouse hat that you would get from Disney World. The genus Tsuga, (hemlock) has pollen that is spherical in shape with an exine that appears to possess a fringe.
Pine pollen begins to show up in our collections in the Birmingham, Alabama area in early to mid-February. Our pine trees do not begin shedding pollen until later in the year so our first collections of pine pollen are the result of pollen being blown into our area from warmer locations south of Birmingham. By March we will begin to have pollen from our local pine trees showing up in our collections and the pine pollen counts can get extremely high during periods in March and early April.
Pine pollen is produced in such large amounts in our area that it often forms layers of yellowish-green dust on cars and objects that are outside. You will often see it floating in puddles following a rain shower in the spring. Even though there are high concentrations of pine pollen in the air during the springtime it does not pose a significant allergenic threat for most people. This is partially due to the size of pine pollen grains, 45-85 microns, that cause them to settle out of the air very quickly. Also, pine pollen doesn’t seem to be highly allergenic and thus pine pollen allergies are rare. Because of the rarity of allergy to pine pollen it is not part of the panel of allergens screened by allergists in skin prick tests. Allergic reactions such as hay fever experienced during the spring are often blamed on pine pollen, but is in fact much more likely due to one of the other tree pollens that are produced in large concentrations during the springtime, for example, oak, mulberry, hackberry, etc. If you think you may have a pine pollen allergy, then be sure to consult your allergist and ask for advice on options available to you.
Loblolly needles in groups of three:
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Longleaf needles in groups of three:
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Longleaf Pollen – note air bladders that give the pollen grain the “Mickey Mouse” appearance.
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