is characterized among monocotyledonous plants by the presence of an unbranched stem bearing a tuft of leaves at the extremity only, or with the leaves scattered; these leaves, often gigantic in size, being usually firm in texture and branching in a pinnate or palmate fashion. The flowers are borne on simple or branching spikes, very generally protected by a spathe or spathes, and each consists typically of a perianth of six greenish, somewhat inconspicuous segments in two rows, with six stamens, or pistil of 1–3 carpels, each with a single ovule and a succulent or dry fruit, never dehiscent (fig. 1, A and B). The seed consists almost exclusively of endosperm or albumen in a cavity in which is lodged the relatively very minute embryo (fig. 1, C). These are the general characteristics by which this very well-defined order may be discriminated, but, in a group containing considerably more than a thousand species, deviations from the general plan of structure occur with some frequency. As the characteristic appearances of palms depend to a large extent upon these modifications, some of the more important among them may briefly be noticed.
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| Fig. 1, A, B.—Floral diagrams of a Palm (Chamaerops humilis). | |
| A, | male flower. B, female-flower. |
| C, | Upper portion of Coco-nut seed, showing 𝑒, embryo, embedded in 𝑎, endosperm. |
Taking the stem first, we may mention that it is in very many palms relatively tall, erect, unbranched, regularly cylindrical, or dilated below so as to form an elongated cone, either smooth, or covered with the projecting remnants of the former leaves, or marked with circular scars indicating the position of those leaves which have now fallen away. It varies in diameter from the thickness of a reed (as in Chamaedorea) to a sturdy pillar-like structure as seen in the date-palm. Palmyra palm (fig. 7) or Talipot. In other cases the very slender stem is prostrate, or scandent by means of formidable hooked prickles which, by enabling the plant to support itself on the branches of neighbouring trees, also permit the stem to grow to a very great length and so to expose the foliage to the light and air above the tree-tops of the dense forests these palms grow in, as in the genus Calamus, the Rattan or Cane palms. In some few instances the trunk, or that portion of it which is above ground, is so short that the plant is in a loose way called “stemless” or “acaulescent,” as in Geonoma, and as happens sometimes in the only species found in a wild state in Europe, Chamaerops humilis. The vegetable ivory (Phytelephas) of equatorial America has a very short thick stem bearing a tall cluster of leaves which appears to rise from the ground. In many species the trunk is covered with a dense network of stiff fibres, often compacted together at the free ends into spines. This fibrous material, which is so valuable for cordage, consists of the fibrous tissue of the leaf-stalk, which in these cases persists after the decay of the softer portions. It is very characteristic of some palms to produce from the base of the stem a series of adventitious roots which gradually thrust themselves into the soil and serve to steady the tree and prevent its overthrow by the wind.
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| Fig. 2.—Daemonorops Draco (a Rattan Palm). |
| 1, Young shoot much reduced. 2, Part of stem bearing male inflorescence. 3, Part of female inflorescence. 4, The same bearing ripe fruits. 2, 3, 4, one-fourth nat. size. |
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| (After Bentley and Trimen, Medicinal Plants, by permission of Messrs J. & A. Churchill.) | |||
| Fig. 3.—Areca Palm (Areca Catechu). | |||
| 1, | Tree, very much reduced. | 5, Male flower opened by removal of a petal. | |
| 2, | Part of leaf, half nat. size. | 6, Fruit, half nat. size. | |
| 3, | Portion of inflorescence with male flowers above, female (larger) below, half nat. size. |
7, 8, Same cut across, and lengthwise, p. Fibrous pericarp; en, ruminated endosperm; e, embryo. | |
| 4, | Petal of a male flower. | ||
The underground stem of some species, e.g. of Calamus, is a rhizome, or root-stock, lengthening in a more or less horizontal manner by the development of the terminal bud, and sending up lateral branches like suckers from the root-stock, which form dense thickets of cane-like stems. The branching of the stem above ground is unusual, except in the case of the Doum palm of Egypt (Hyphaene), where the stem forks, often repeatedly; this is due to the development of a branch to an equal strength with the main stem. In other
