An ability to recognize the important hay fever grasses and a knowledge of their location and pollinating periods is an asset to any hay fever sufferer. There are as many as 1500 different kinds of grasses in the United States, and the pollens of any of them can cause symptoms in a sensitive individual, but only about a dozen different grasses have been indicated to be significant in the cause of hay fever.
By applying to the grass pollens his five postulates and checking them against the results found by many investigators, Thomen listed three groups of hay fever grasses according to their relative importance. In the last ten years these groups have been slightly modified by the results of further observations. And so at the present time we can group the grasses into classes of first, second, and third degree offenders. Such groupings of offending hay fever plants are of course always relative to the area by which you are bound in your discussion. For, as pointed out previously, a plant which is the chief cause of hay fever in one region may be non-existent in another.
Among the first rate grass offenders in the United States must be classed timothy and June grass representing the North, and Bermuda grass for the South. These three grasses are considered to be responsible for 90 percent of the grass hay fever in the United States.
A group of somewhat lesser importance whose members often take first place in specific localities includes sweet vernal grass, orchard grass, red top grass, Johnson grass, velvet grass and couch grass.
The grasses of minor importance are meadow fescue, spear grass, panic grass, canary grass and rye grass.
THE IMPORTANT GRASSES
Timothy. This grass is the most important cultivated hay plant in the northern part of the United States. It is used extensively to supply hay for cattle and horses. It is generally grown in huge tracts of land, in which areas, it causes much hay fever from the last week in June to the last week in July. The plant derives its name from Timothy Hansen, who is supposed to have brought it from New England to Maryland during colonial days. Timothy grass is easily recognized by its flowering head of close set spikelets that give it the appearance of the punk, that kids use to light their firecrackers on the Fourth of July.
June Grass. June grass, sometimes called Kentucky blue-grass, green grass, or meadow grass, is primarily cultivated to supply food for grazing animals in pastures. It is used widely as an excellent lawn or sod grass because of its ability to live a long time. It is frequently used for golf courses and lawn tennis courts in the northern states. It is also a very hardy grass, growing in roadsides, ditches, and gardens without any cultivation and consequently often causes hay fever symptoms among people living in and near cities during the height of its pollination period in June. In distribution June grass is closely related to Timothy, covering the entire northern two thirds of the United States. It is a cause of hay fever in every state except North Carolina, Alabama, Georgia, Florida, Utah and Mexico.
June grass pollinates during late May, through June, and into early July. Its flowering head or inflorescence as it is called takes a typical open triangular form.
Bermuda Grass. This is the principal hay fever grass of the South. Like June grass it is cultivated as a grazing food for cattle and horses. Bermuda grass is very tenacious withstanding drought and trampling much better than June grass. Because of its tenacity and hardiness it is used as a lawn grass for golf courses and tennis courts throughout the South. Swinging a golf club on a Southern fairway which is unclipped is madness if you are allergic to grasses.
Bermuda grass has the longest pollinating period of all the grasses. It pollinates from May to September, and in some places almost all year-round. It is found clear across the United States from east to west in the southern states.
Like the other grasses, Bermuda grass has its aliases, having been called devil grass, wire grass, scutch grass and Yankee grass. Its scientific name dactylon, is descriptive of its appearance. The word dactylon, coming from the Greek meaning finger, describes the finger-like projections of the flowering heads of the stem.
Red Top. Red top may be considered a first cousin to timothy grass. It is not nearly as much cultivated as June grass or timothy, however, it is used as a supplement to these grasses in soils too moist for them. It is grown in New England, the North Atlantic states, Missouri and Mississippi.
Red top pollinates during the same period as timothy, from about the last week in June to the last week in July. With the termination of the pollination of these two grasses you have the end of the summer hay fever season in the northeastern part of the United States. The plant is easily recognized by its loosely arranged, pyramid shaped, reddish flowering heads from which it takes its name. See Fig. 5.
Sweet Vernal. As its name implies, this grass is characterized by its sweet smelling vanilla-like odor that it gives off. But it also gives off some pollens from the middle of May to the middle of June. Although not cultivated to any extent, it grows throughout the eastern quarter of the United States excepting Michigan and Florida. It is most abundant in the northeastern states.
Orchard Grass. Orchard grass extract combined with the extracts from June grass, timothy, red top and sweet vernal makes up a common mixture that doctors often use in giving immunizing inoculations against summer hay fever. Orchard grass is grown in every state in the Union but not in any great abundance. It derives its name from its ability to grow well in shady places. The flowering heads form bunches at the top of stems two to four feet tall. It pollinates at the same time as June grass, from the end of May to the last week in June.
A detailed description of the remaining grasses of lesser importance in causing hay fever would be of little interest in general. Such grasses are often mentioned in the literature as causes of hay fever symptoms in particular localities. Therefore we shall only touch on each of these as a guide for further exploration which some readers may desire to undertake.
THE LESS IMPORTANT GRASSES
Johnson Grass pollinates in the South during July, Au-gust and September. Its pollens are too heavy to be sustained in the air and thus symptoms from this grass are light and occasional. Meadow grass often occurs with June grass and is known to pollinate at the same time. Velvet grass has been reported as a cause of hay fever in the Pacific Northwest. In New York where it is also found it is seen to pollinate from the middle of June to the first week in July. Couch grass pollinates at the same time as velvet grass. It is spread throughout the United States but is more abundant in the New England states where it is often mixed in with timothy hay. Of the hay fever grasses, low spear grass is said to be one of the earliest to pollinate.
It is considered a minor cause of hay fever in the east but more prevalent in California. Another cause of hay fever in California is Rye grass which pollinates there during May and June. Canary grass whose name comes from the fact that its seed is the favorite food of the canary is of very slight importance in the cause of hay fever. It is found chiefly in the Southern states.
There are many other grasses that have been reported to be of some slight importance in specific localities. However, they are too numerous to include here, and a description of them would serve only to confuse the reader.