De bouw der klieren van enige Polygonumsoorten en -bastaarden

An anatomical study was made of the glands of some dutch Polygonaceae to test their taxonomic value. The following species were investigated: Polygonum Persicaria, P. minus. P. lapathifolium, P. mite and P. Hydropiper. Moereover the hybrids P. Persicaria X minus, P. Persicaria X mite. and P. minus X Hydropiper were studied. A short description of the main characteristics of the different types of glands will be given here. I. Pol. Persicaria. Leaf. Pluricellular sessile disk-shaped green glands, one cell deep, on the lower side; each lying in a little depression of the leaf, attached to small epidermal cells, (figures i, 2). Flower. On some flowers pluricellular yellowish glands. Stalk of the inflorescence. Sometimes a few stalked glands, (figure 3). Young 0 c hr e a. Sometimes a few pluricellular sessile glands on the outside. In some individuals all glands are lacking. 2. Pol. minus. Leaf. Pluricellular sessile disk-shaped glands on the lower side, composed of one layer of cells, bluegreen, surrounded by a transparent non-cellular layer, attached to small epidermal cells, (figure 4). Flower. On some flowers a few pluricellular yellowish glands. Young 0 c hr e a. A few pluricellular bluegreen glands on the exterior. 3. Pol. lapathifolium. The subspec. tomentosum, nodosum and mesomorphum show glands of a corresponding type. Leaf. Glands especially on the lower side numerous, each placed in a small depression, sessile or with very short stalks, spherical or ellipsoid, composed of 2-3 layers of cells, green, often covered with a yellow or brown, sometimes amberlike, substance, (figure 5). Flower. Glands pluricellular, sessile or shortstalked, spherical, yellow or yellowish brown, (figure 7). Stalks of the inflorescences. A large number of longstalked glands. O c hr e a. Long-stalked glands on the exterior and along the margin (figure 6). 4. Pol. mite and Pol. Hydropiper. Both the species possess sunken glands in leaves, flowers and ochrea. In. P. Hydropiper their number is much larger than in P. mite. Moreover the glands of P. Hydropiper are filled with a drop of liquid, whereas the foliar glands are visible as bright yellowishspots when the leaf is held up to the light. Both these characteristics are lacking in P. mite. P. mite Leaf. Glands lying among the epidermal cells, composed of a spherical cavity which is surrounded by 4-6 cells, (in up till to cells) bean-shaped in transverse section. The surrounding epidermal cells are much smaller and more regular than the others (figures 8, 9, 11). Flower. Glands much larger than in the leaves, (figure 10). 5. Pol. Persicaria X minus. Leaf. Glands like those of P. minus, but coloured green. Transparent layer often lacking in older leaves, (figures 12, 13). 6. Pol. minus X Hydropiper (figures 17, 18, 19). Pol. Persicaria X mite (figures, 14, 15, 16). Pol. minus X mite (figure 20). Leaf. Glands lying within a circle of small epidermal cells, pluricellular, composed of one layer of cells, green. Cells often arranged in 2 rows. Tangential section looks like the sunken glands of Pol. Hydropiper or Pol. mite when seen from above. There are only minor differences between these three hybrids. Usually the glands of Pol. minus X Hydropiper are composed of 4-6 cells, those of Pol. Persicaria X mite of 8-10 cells, whereas Pol. minus X mite often shows 6 cells. Results of this investigation. Each of the species of Polygonum mentioned was shown to have a very specific type of gland by which they are easily identified. The hybrids possess a shape of gland deviating from all species, but taken as a group the glands of the 3 hybrids are virtually identical.