Oleaceae Olive Tree Family

Two predominant anemophilous plants producing allergenically significant pollens belong to the genera Fraxinus (ash) and Olea (olive tree). The latter one is also an important source of olive oil.

Fraxinus excelsior is widespread in north western and central Europe. Olea europea trees are common in the Mediterranean. Fraxinus flowers mostly in spring, during April and May. Olea europea flowers in May and June. Pollen grains are sub-oblate, tricolpate, measuring about 20 mm in size and possess reticulate wall. Severe symptoms of pollinosis are observed from Olea pollen.

Betula - Birch

The trees of this genus are a favourite with landscape architects on account of their ornamental value, white stems and drooping branches. The trees are most dominant in Nordic countries forests, western and central Europe. The most common species of Betula are B. verucosa (B. pendula) and B. pubescens. The male catkins are pendulous, yellow green in colour. In contrast, female catkins are erect and green.

Normal flowering of this plant is from April to the first half of May. However, sometimes delayed flowering from May to June is also observed, particularly in Nordic countries.

Betula pollen grains are sub-oblate to spheroidal, triporate with small onci, measuring 20-25 mm (Fig. 5.10).

Chenopodium, Amaranthus - Pigweed

Airborne pollen of Chenopodiaceae and Amaranthaceae cannot be distinguished from each other and hence they are always mentioned together as they are morphologically similar.

Amaranthus is widespread in southern Europe. It usually flowers in summer. The pollen grains are spheroidal, pantoporate, with as many as 60-80 pores and measure around 25-30 mm (Fig. 5.11). The pollen exhibit allergic sensitivity, but the significance for symptoms of pollinosis is considered to be rather small.

Artemisia - Mugwort

Similar to Ambrosia, Artemisia also belongs to the family Asteraceae. It grows abundantly on disturbed soils. The most common spp. is A. vulgaris. The other two species A. annua and A. verlotorum are also common. In addition, the pollen of sage brush or Artemisia tridentata is known from the state of Missouri. The pollen of ragweed and sage brush cause severe allergic symptoms. However, both these show a very high degree of cross reactivity. In addition, the cross reactivity is also shown between giant and short ragweeds.

It flowers from the end of July to September. The plant produces allergenic pollen, which are oblate, spheroidal, about 20 mm in diameter, tricolporate.

Show Oxalis Amaranth
Fig. 5.11 Pantoporate pollen of Amaranth Chenopod (SEM).

Rumex - Sorrel

The plants of this genus are mostly weeds growing on wet soils found all over Europe. The plant bears red coloured, bisexual inflorescence often giving the meadow landscape a very attractive aspect. Rumex crispus is the most common species. Pollen grains are oblate, spheroidal, tricolpate with narrow furrows, measuring 20-30 mm. Pollen is mildly allergenic.

The other pollen which have been illustrated are Erica or Heather (Fig. 5.12), Tilia or Lime (Fig. 5.13) and Plantago or Plantain (Fig. 5.14).

Pollen morphological descriptions of selected european plants have been summarised in tabular form in Table 5.1.

Table 5.1 Pollen morphological description of selected European pollen in tabular form.

Table 5.1 Pollen morphological description of selected European pollen in tabular form.

Name

Grains

Exine

Furrows

Pores

Intine

Interior

Artemisia vulgaris L.

Mugwort

Asteraceae

Tricolporate, Spheroidal, Small 16.9 x 17.9 mm

Thick up to 2.9 mm in middle of intercolpia ectexine

Three, 2.0 x 4.7 mm narrowing outside the pore to 3.4 mm

Three, one in the middle of each furrow, elliptical

Thick

Carex caryophyllea L. Spring sedge Cyperaceae

Inaperturate, pyriform, medium sized to large, length 37.0 mm, width at greatest 27.3 mm

Thin

Upto 5 mm thick Poroids - an indistinct rounded aperture - usually one at thick end of grain and 3 on sides. Exine thinat these points

Chenopodium album L. Fat hen

Chenopodiaceae

Porate, spheroidal, small 25.8 mm

Medium ectexine thicker than endexine, thicker between pores forming a wavy outline in optical section

50-70 evenly scattered over whole surface 1.7-3.0 mm apart, circular 2.5 mm diameter, surface smooth except for small operculum

Thin

Corylus avellana L. Betulaceae

Porate, suboblate or subtriangular, aspidate, small 20.2 x 24.8 mm

Thin, thickened a little round pores, raised to form aspis 10.2 mm diameter. Ectexine thicker than.

Three, evenly spaced around equator, circular to slightly elliptical 2.6 mm diameter

Thin, swelling beneath pores to more or less markedly convex onci, 10.1 x 5.6 mm

Table 5.1 Contd.

Name

Grains

Exine

Furrows

Pores

Intine

Interior

endexine, surface smooth or slightly granular

Galium mollugo L. Great Hedge Bedstraw Rubiaceae

Colpate, suboblate or oblate, spheroidal, small 16.6 x 18.9 mm

Medium, ectexine equalising endexine, surface faintly reticulate

Seven or eight 11.5 x 1.6 mm acute

Thin

Heracleum sphondylium L. Cow Parsley,

Tricolporate, medium sized

Thick, ectexine thicker than endexine, comprising thick rods

Three, 2.0.0 x 2.3 mm narrowing, long, acuminate

Transverse, three, one in middle of each principal furrow

Thin

Juncaceae common rush Juncus acutiflorus Hoffm. Sharp flowered Rush Juncaceae

Compound (tetrads) 40.7 mm

Constituent grains: more or less spheroidal, inaperturate, united in tetrahedral tetrads, small 25.6 mm

Thin, large thin areas (poroids) of discrete

Thick below poroids, thin granules elsewhere

Quercus robur L. English Oak Fagaceae

Tricolpate, oblate to spheroidal, small-medium sized 20.7 x 28.9 mm

Thin, ectexine thicker than endexine, surface warty-granular

Three, 16.0 x 7.6 mm tapering membrane protruding

Medium thickness

Table 5.1 Contd.

Name

Grains

Exine

Furrows

Pores

Intine

Interior

Rumex crispus L.

Curled

Dock

Polygonaceae

Colporate, oblate to spheroidal, small to medium sized 28.0 x 29.2 mm

Medium thickness, ectexine thicker than endexine -thicker around pores. Surface finely reticulate.

Three, rarely four, longitudinal 22.2 x 1.3 mm, tapering

Three, rarely four, one in the middle of each furrow, narrowly elliptical

Thin

Packed with tiny starch granules

Salix caprea L. Goat Willow Salicaceae

Tricolpate, oblate, spheroidal, small 15.0 x 16.4 mm

Thin, ectexine thicker than endexine, surface reticulate, medium sized in middle of intercolpia becoming smaller towards poles

Three, 12.5 x 4.0 mm, acute membrane protruding beyond outline of grain

Thin

Senecia jacobea L. Ragwort Asteraceae

Tricolporate, oblate, spheroidal, echinate, small 20.4 x 21.5 mm

Medium thickness, surface granular, sharply pointed spines, 2.2 mm high, 1.7 mm broad at base

Three, 18.2x6.0 mm, abruptly narrowing

Three, one in middle of each furrow, Circular 6.0 mm membrane protruding

Thin, thickening over surface of pore

Urtica dioica L. Nettle Urticaceae

Porate, spheroidal, small 13.4 x 14.5 mm

Thin, slightly raised round each pore forming aspis, surface smooth

Three or four, equally spaced around equator, circular 1.6 mm diameter

Thin, swelling beneath pores forming onci

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