Pearl gland

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On the underside of the leaf and on the stem of the Mallorca nettle ( Urtica bianorii ) there are about 0.2 mm large pearl glands, at the base of which there is usually a small glandular hair .

Pearl glands are usually spherical or elongated hair cells in plants that can reach a diameter of up to 1 mm.

Origin and construction

At the foot of a pearl gland there is often a cleft opening , which is filled with a few large vacuoles inside cells. One of these inner cells increases in volume and grows wart-like and later roundish in height. You always remain surrounded by the initial neighboring cells. The interior of the pearl gland is characterized by inner cells poor in chloroplasts , which only have lipid droplets in their vacuoles .

In the great nettle ( Urtica dioica ), the pearl gland often forms a compound hair with a small glandular hair located at the base .

function

The Perldrüse separates from an aqueous liquid, which is why it as a special form the trichome - hydathodes is assigned.

Occurrence

Perldrüsen were on young shoots of the grapevine ( Vitis vinifera ) and parthenocissus ( Parthenocissus be found). Here they occur especially in strong elongation growth and warm, humid weather. Pearl glands are also found on some nettles, such as the great nettle ( Urtica dioica ), the tailed nettle ( Urtica membranacea ) and the Mallorca nettle ( Urtica bianorii ). On the other hand, there are no pearl glands on the small nettle ( Urtica urens ). No studies have been carried out on the pearl glands of other nettles. In the greater nettle, pearl glands appear particularly numerous at low humidity and recede at 100% humidity.

swell

  • Margareta Mathwieser, Helmut Guttenberger: Nuclear DNA content of the pearl glands and the stinging hairs of Urtica dioica L. In: Phyton (Horn). Volume 27, No. 1, 1987, pp. 93-98 (PDF file).
  • Margareta Mathwieser, Irmtraud Thaler, Manfred Gailhofer: The pearl glands of Urtica dioica L. In: Phyton (Horn). Volume 27, No. 1, 1987, pp. 99-113 (PDF file).
  • Gabriella Corsi, Francesca Maffei: Urtica membranacea pearl glands. I. Morpho-ontogenetic and histochemical aspects. In: Phyton (horn). Volume 32, No. 2, 1992, pp. 235-245 (PDF file).
  • Gabriella Corsi: Urtica membranacea pearl glands. II. - Some Aspects of Nuclear Metabolism. In: Phyton (horn). Volume 34, No. 1, 1994, pp. 95-102 (PDF file).

Web links

Commons : Pearl bodies  - collection of pictures, videos and audio files