Hay fever allergies can occur when pollen from flowers is spread in the air and breathed in through the human nose. Pollen is from the male part of the flower (Yes you can blame it on males); and flowers that are wind pollinated disperse their pollen into the air to search for the female part of another flower.
But many flowers are pollinated by insects, and thus do not shed pollen into the air. Also the double flowered forms of many flowers have lost their pollen producing parts in the process of making the extra petals that make them double flowers. These flowers are low allergy risk flowers, as little if any pollen is in the air from them.
If you are sending flowers to people who suffer from hay fever ask for low allergy risk flowers in the bouquet. Here are the flowers which you can request for allergy sufferers.
Roses; Hydrangea; Gladioli; Orchids; Peonies; Carnations; Iris; double forms of Chrysanthemum; Tulip