Pollen of timothy grass, Phleum pratense
Numéro d’image : 13444788
| Scanning electron micrograph of pollen grains of timothy grass, Phleum pratense. The picture shows six grains, two with a germination pore visible (red). The pore is the site within the wall through which the pollen tube emerges when the grain encounters a female stigmatic surface. The tube conveys the male gametes to the ovaries. Grasses are wind-pollinated plants, although hoverflies may sometimes effect pollination. The grains are light and very small - about 30 microns across. They are shed in large numbers and usually travel only a few metres from the plant. Many will fail to reach their intended destination - a female floret; but once airborne, they may cause allergic rhinitis - hay fever"" - in susceptible humans. Rarely, convection currents can carry pollen to a height of 1km above ground. P. pratense is the most common cause of hay fever in the grass pollen season." | |
| Licence : | Droits gérés |
| Crédit: | Science Photo Library / Burgess, Dr. Jeremy |
| Taille de l’image : | 3468 px × 5212 px |
| Model Release : | Non requis |
| Restrictions : | - |
Prix pour cette image À partir de 45 €
Produit vendu
(Calendrier, Carte postale, Carte de vœux, Impression sur textile, Packaging etc)
À partir de 45 €
Usage commercial
(Affichage, Annonce presse, Annonce TV, Carte, Digital - hors rés. sociaux, Digital - rés. sociaux etc)
À partir de 45 €
Éditorial
(Digital, Journal, Livre, Livre pratique, Magazine, Télévision etc)
À partir de 60 €
Usage non-commercial
(Digital - hors rés. sociaux, Digital - rés. sociaux etc)
À partir de 120 €