Stipule
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The stipules (stipules or stipules), even after sheets are sheet-like outgrowths of the sheet substrate of many plant species, that is the lowermost part of a leaf blade , to which it is attached to the stem. They are an important determinant . Some plant families lack stipules (exstipulate).
In the dicotyledonous , the stipules always occur in pairs, to the right and left of the leaf base. On the picture on the right you can see a leaf of the dog rose ( Rosa canina ), in which the two stipules have grown together with the leaf axis. In the monocot the stipules are apparently axillary. In sweet grasses , they are formed as a small membrane ( ligula ) at the upper end of the leaf sheath .
The stipules can be very different:
- Lateral stipules (lateral, free lateral), to the right and left side, to the side of the leaf base, the stipples are directed outwards instead of along the petiole, this is also called "extrapetiolar". They can also be directed downwards or upwards or they can be grown together around the stem or half of the stem.
- As a pair of wings fused to the stem (adnate), as in roses ( Rosa ).
- In some butterflies (Fabaceae, order Fabales) the stipules have approximately the shape of the normal leaflets. In most of the red plants native to Europe, the stipules have the same shape as the opposite leaves, here they appear in pseudo whorls .
- In the black locust ( Robinia pseudoacacia ) the side sheets are thorns (Nebenblatt thorns) (spinous) converted.
- In most Rötegewächsen and Cunoniaceae are in counter or quirlständiger blade position the stipules of adjacent, continuous, or against wirteliger sheets in a uniform, adherent structure between the sheets arranged on the stem. In this case the term interpetiolar stipules is used .
- In some plants, the stipules can also be arranged between the leaf axil and the stem, so that one then speaks of intrapetiolar stipules .
- If the stipules are united in the center, they are called median stipules or axillary stipules (ligula). On petioles they unite to form a tongue or hood-shaped structure in a median position; Houttuynia cordata , Schefflera actinophylla .
- In the knotweed family , the stipules are fused to form a membranous sheath (stipple, stipple sheath) ( ochrea ), which encompasses the stem (amplexicaul).
- Stipules can also be designed as tendrils, as in the stinging winds ( Smilax ).
- They can also be fused into a single large leaf (foliaceous, antidromous). As with the vine pea ( Lathyrus aphaca ), here they take on the photosynthetic function of the leaves, since the leaf blade is transformed into tendrils.
- They can also occur ventrally (convolute), i.e. H. they are on the ventral side at the base of the leaf stem, as in magnolias . They also act as bud scales here.
- They can also occur as bud scales (scaly), they are dry, small, membranous scales. Normally, two at the leaf base, as in Spergel ( Spergula ).
Have the leaflets at pinnate leaves and small, in addition to sheet-like or spur-like outgrowths (low platelets, secondary adrenal leaves), they will be as stipel or Stipella (e) , Stipellen designated.
A distinction is also made between pseudo- stipules or, when approaching real stipules , metastipules ; these are basal segments of the leaf surface, in contrast to the normal stipules; basal separation of the leaf base.
Leaves (pre-leaves) ( Aristolochiaceae , Solanum ) or leaflets ( Trichilia , Meliaceae ) or bud scales ( Bignoniaceae ) that appear like stipules are also understood as pseudo-bracts .
"Paraphyllidia" occur in the mimosa family . Reduced, stipella-like leaf structures on the rachis or often at the pinnate attachment of the pinnate leaves.
Leaves and leaf-like, interpetiolar stipules in a whorl in Galium odoratum
Stipules transformed into thorns in Prosopis pallida
In Lathyrus aphaca , the leaves are transformed into tendrils and the stipules are leaf-like
Pinnate leaf with stipules and stipules
Leaves of the rain tree ; you can see the horn-like "paraphyllidia" in the close-up
Median or here axillary stipules in Schefflera actinophylla , clearly visible in the close-up
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The stipules are also differentiated according to their lifespan:
- Lapsed (caducous): such stipules fall off before or shortly after the lamina unfolds.
- Deciduous: such stipules fall off after the lamina has unfolded.
- Permanent, permanent (persistent): such stipules are permanent, constant.
Web links
- Stipules and Stiples ( Memento from April 8, 2016 in the Internet Archive ), at The Mildred E. Mathias Botanical Garden (MEMBG).
Individual evidence
- ↑ Max Römer : Handbook of general botany. First department, Fleischmann, Munich 1835, p. 154, digitized .
- ↑ Ashok Bendre, Ashok Kumar: A Text Book Of Practical Botany. Vol. II, 7th Edition, Rastogi Publications, New Delhi 2008, ISBN 81-7133-877-1 , p. 19 f.
- ↑ Jan W. Moll: Phytography as a Fine Art. Brill, Leiden 1934, p. 134.
- ↑ Beth Ellis, Douglas C. Daly et al. a .: Manual of Leaf Architecture. New York Botanical Garden Press et al. a., Ithaca NY et al. a. 2009, ISBN 978-0-8014-7518-4 , p. 9.
- ↑ Gottlob Christian Reuss: Plant leaves in natural print. Schweizerbart, Stuttgart 1869, p. 158, digitized .
- ↑ Lothar Geitler : Morphology of Plants. 3rd edition, De Gruyter, 1953, 2019, ISBN 978-3-11-100744-1 (reprint), p. 122.
- ^ Josef Schiller: Studies on stipular formations. In: Session reports of the Imperial Academy of Sciences: Mathematical and natural science class. Volume 112, Division I, Session XX, Vienna 1903, pp. 793-819; Panels I – III, biodiversitylibrary.org , PDF (2.5 MB) on ZOBODAT