Читать книгу Field and Woodland Plants - William S. Furneaux - Страница 9

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We must now turn our attention to the different kinds of inflorescence or arrangement of flowers. Flowers are commonly mounted on stalks (peduncles), but in many cases they have no stalks, being attached directly to the stem of the plant, and therefore said to be sessile. Whether stalked or sessile, if they arise from the axils of the leaves—the angles formed by the leafstalks and the stem—they are said to be axillary. When only one flower grows on a stalk it is said to be solitary; but in many cases we find a number of flowers on one peduncle, in which instances, should each flower of the cluster have a separate stalk of its own, the main stalk only is called the peduncle, and the lesser stalks bearing the individual flowers are the pedicels.

Various Forms of Simple Leaves

1. Oval or elliptical. 2. Ovate. 3. Obovate. 4. Orbicular. 5. Lanceolate. 6. Linear. 7. Cordate (heart-shaped). 8. Obcordate. 9. Reniform (kidney-shaped). 10. Sagittate (Arrow-shaped). 11. Rhomboidal. 12. Spathulate (spoon-shaped). 13. Peltate (stalk fixed to the centre). 14. Oblique. 15. Runcinate (lobes pointing more or less downwards). 16. Hastate (halberd-shaped). 17. Angled. 18. Palmate. 19. Pinnatifid.

Forms of Compound Leaves

1. Binate. 2. Ternate. 3. Digitate. 4. Pinnate.

Forms of Inflorescence

1. Spike. 2. Raceme. 3. Corymb. 4. Umbel. 5. Cyme. 6. Compound Raceme or Panicle. 7. Capitulum or Head. 8. Compound Umbel.

It is often convenient to make use of certain terms to denote the various arrangements of flower-clusters, and the principal of these are as follows:—

1. Spike.—Sessile flowers arranged along a common axis.

2. Raceme.—Flowers stalked along a common axis.

3. Corymb.—Flowers stalked along a common axis, but the lengths of the pedicels varying in such a manner as to bring all the flowers to the same level.

4. Umbel.—The pedicels all start from the same level on the peduncle.

5. Cyme.—An arrangement in which the flower directly at the end of the peduncle opens first, followed by those on the branching pedicels.

6. Panicle.—A compound raceme—a raceme the pedicels of which are themselves branched.

7. Capitulum or Flower-head.—A dense cluster of flowers, all attached to a common broad disc or receptacle.

Other forms of inflorescence may also be compound. Thus, a compound umbel is produced when the pedicels of an umbel are themselves umbellate.