Palm Characteristics and Anatomy

have long internodes ; l sparsely branched is, e.g. the African Doum-palm (Ilyphcene). Notwithstanding their often enormous stems the Palms have fibrous roots, like the bulbous Monocotyledons. The leaves are pinnate (Feather-palms, Fig. 298) or palmate (Fan- palms, Fig. 295) and often very large; they have a well-developed petiole with an amplexicaul sheath, which is often more or less separated into a large number of fibres. In the bud the blade is entire but folded, as the leaf expands the lines of folding are torn, either those which are turned upwards (thus V V V V , e.g. Pritchardia, Livistona, Phoenix, Chamcerops) or those turned down- wards (thus A A A A, e.g. Gocos, Chamcedorea, Calamus). The inflorescence is usually lateral ; when, as in Sago-palm (Me- troxylon rumphii) or Talipot (Corypha umbraculifera) it is termi- nal, the plant is monocarpic, and dies after flowering; it is often a very large and branched spadix with numerous flowers either borne externally or embedded in it, and enclosed either in one woody, boat-shaped spathe (Fig. 2Q7) or several spathes, in the latter case one for each branch. The flowers are sessile or even embedded, regular, generally unisexual (monoecious or dicecious) with the usual diagram (Fig. 278) ; the perianth is inconspicuous, green or yellow, persistent, and more or less leathery or fleshy. 6, rarely 3 or many stamens. The 3 carpels remain either distinct or form one, generally 3-locular, ovary. The style is short. There is one ovule in each carpel. Often during ripening 2 carpels with their ovules are aborted. The fruit is a berry, drupe or nut, generally one-seeded, with a large horny or bony endosperm with hard thick-walled cells (e.g. Date-palm). In some (e.g. Cocoanut) it is thin-walled, soft, and oily; in several " ruminate." When germination commenced in the Cocoanut, Date, etc., the apex of the cot \ledon remains in the seed and developesinto a spongy mass to withdraw the endosperm ; in the Cocoanut it attains a considerable size (Fig. 299 C) and 1 [Although unbranched stems are characteristic of the Palms, yet branched specimens are recorded from some eleven genera. The branches are developed from lateral buds, which in many instances only develope when the terminal bud has been destroyed. A few Palms develope axillary branches at the base of the stem ; these form rhizomes, and give rise to clusters of aerial stems.] SPADICIFLOR.E. 299 assumes the form of the fruit. The endosperm in the Cocoanut is hollow and the interior is filled with "milk." In the Date-palm and the Vegetableivory (Phytelephas) the cell-walls of the hard endosperm serve as reserve material. I. PH<ENICEJ:. Phoenix (Date-palm) has pinnate leaves with channeled leaflets and dioecious flowers with 3 free carpels, of ' FIG. 297. Inflor- escence of a Palm with spathe. At the top <?-, at the base ? -flowers. FJG. 208. Livistona australis. wKich usually only one developes into a berry with membranous endocarp ; the large seed has a deep furrow on the inner side, and horny endosperm. 2. SABALE.S;. These have fan-like leaves with channeled seg- 300 MONOCOTYLEDONES. ments ; flowers ^ or polygamous, rarely dioecious, with 3 separate or only slightly united carpels, all of which are sometimes developed into fruits (berry or drupe, with thin stone). Chamcerops, the Dwarf-palm. The pericarp is externally fleshy, internally more fibrous, and provided with a membranous inner layer. The endosperm is ruminate (that is, the testa is several times deeply folded into the endosperm). Sdbal, Copernicia, Livistona (Fig. 298), Thrinax, Corypha, Brahea, and others. ^ IG. 299. A Longitudinal section of a Cocoannt (diminished), the inner layer only (the stone,) not being divided B End view of the stone, showing the sutures for the 3 carpels (a), and the 3 germ-pores ; the embryo emerges from the lowest one when germination begins. C Germinating ; inside the stone is seen the hollow endosperm and the enlarging cotyledon. 3. COCOIJSIE^E. With pinnate leaves. Monoecious inflorescence. The carpels are united into a 3-loo.ular ovary. The fruit is most frequently 1-locular, only 1 of the loculi becoming developed, rarely 3-locular ; it is a drupe with a large, fibrous, external layer (mesocarp) and most frequently a very hard inner layer (endocarp, stone) which has 3 germ-pores, the 2 of .these, however, which correspond to the suppressed loculi are closed; internal to the third lies the small embryo (Fig. 299). Endosperm containing SPADICIFLOR^;. 301 abundance of oil. Cocas (the Cocoannt-palm), Attalea, Elceis, Acrocomia, Bactris. 4. LEPIDOCARYIIO;. The floral-leaves and flowers are borne in 2 rows on the spadix. The carpels are united into one 3-locular ovary ; the fruit is coated by a layer of hard, shining, imbricate scales. The majority of the species are thorny, and climb by means of the thorny leaves. Some have fan-like (Mauritia), others pinnate leaves (Raphia, Calamus, Eugeissonia, Metroxylon; the stems of the latter die after the first flowering). 5. BORASSIN^E. Large Fan-palms without thorns, with 3-locular ovary. Drupe with separate stones. I.atania and Lodoicea have many stamens ; Hyplicene', Borassus (Palmyra-palm). 6. ARECINEJE. The most numerous group. Feather-palms. Berry. Areca, Euterpe, Oreodoxa, Ceroxylon, Chamcedorea, Geonoma, Caryota with bi-pinnate leaves. 7. PHYTE^EPHANTIN^E. Flowers with rudimentary perianth united in close capitula. Pliyteleplias (Vegetable-ivory). Nipa. DISTRIBUTION. About 1,100 species are known. In Europe only the Dwarf- palm (Chamcerops humilis) is wild (Western Mediterranean). The Date palm (Phce.nix dactylifera) belongs to North Africa and West Asia. Other African genera are Hyphcene (Doum-palm) and Elceis (E. guineensis, Oil-palm). A large majority of the genera are found in South America and in the East Indies. The following are AMERICAN: Mauritia, Acrocomia, Bactris, Chamce- dorea, Oreodoxa, Euterpe, Attalea, etc. ASIATIC : Metroxylon, Calamus, Areca, Borassus, Lodoicea ("Double -cocoanutp," Seychelles) and others. The Cocoanut-palm has perhaps an American origin ; all the other species of the same genus being endemic in America ; it is the only Palm found on the coral islands of the Pacific Ocean, and is also the ouly one which is common to both hemi- spheres. USES. Palms belong to the most useful plants ; they contain no poison, and are of little medicinal interest, but are largely employed in the arts and manufactures, the hard timber being adapted for many purposes on account of the hard tissue in which the vascular bundles are embedded. " Cane " is the stem of Calamus-species (from India). SAGO is obtained from the pith of Metroxylon rumphii (Sago-palm, Sunda-Is., Moluccas), Mauritia flexuosa, etc. Sugar-containing sap (" palm wine ") is obtained from the American Mauritia vinifera and flexuosa, Borassus fiabelliformis (Asiatic Palmyra-palm), Arenga saccharifera, etc., by cutting off the young inflorescences, or by perforating the stem before the flowering (arrack is distilled from this). Vascular strands for the manufacture of mats and brushes, etc., are obtained from the outer cover- ing (mesocarp) of the Cocoanut, and from the detached leaf-sheaths of Attalea WAX funifera (Brazil) (Fig. 296). is yielded by the leaves of Copernicia cerifera (caruaiiba-wax, Amazon region), and by the stem of Ceroxylon andicola (palm-wax, Andes) ; East Indian Dragon's blood is from the fruit of Calamus draco ; the young buds of many species, especially Euterpe, Cocos, Attalea, 64,0., are used as " cabbage." Palm-oil is obtained from the oily mesocarp 302 MONOCOTYLEDONES. of the plum-like fruits of Elceis guineensis (W. Africa), and from the seeds, when it is largely used in the manufacture of soap. EDIBLE FRUITS from tbe Date-palm (Phoenix dactylifera, Arabia, Egypt, W. Africa), and the endosperm of the Cocoa-nut (Cocos nucifera). The seeds and the unripe fruits of the Areca-palm (Areca cateclni) are chewed with the leaves of the Betelpeper, principally in Asia. VEGETABLE IVORY from the hard endosperm of Phytelephas macrocarpa (S. America.) Many species are cultivated in the tropics as ornamental plants, but in this country only Chamcerops humilis, Livistona australis and chinensis are generally grown. In addition to the few just mentioned, many others are of importance, but these are much the most useful. Order 2. Cyclanthaceae. This is a small order related to the Pahus (44 species from Tropical America), with fan-like, folded leaves. The flowers are unisexual and arranged in whorls or close spirals on an unbranched spadix. Ovary unilocular, ovules numerous. To this belongs Carludovica palmata, whose leaves are used for Panama hats. Order 3. Pandanaceae (Screw-pines) is another small order, forming a transition to the Araceae. The woody, (apparently) dichotomous stem is supported by a large number of aerial roots, which sometimes entirely support it when the lower portion of the stem has decayed. The leaves are closely crowded together, and arranged on the branches in three rows, which are often obliquely displaced, with the formation of three spiral lines ; they are, as in the Bromeliaceae, amplexicaul, long, linear, the edge and lower midrib often pro- vided with thorns. The $ -flowers are borne in branched, the ? in un- branched spadices or capitula, which resemble those of Sparganium, but have no floral-leaves. Perianth absent. The drupes or berries unite into multiple fruits. About 80 species in the islands of the Indian Ocean. Pandanus, Fieycinetia. Fossils perhaps in the chalk of the Harz. Order 4. Typhacese. The flowers are unisexual, monoecious^ and borne on a cylindrical spike or globose capitulura ; $ inflorescences above, the $ below. The perianth consists of a definite number of scales (^Sparganium), or in its place numerous irregularly-arranged hairs are found (Typha) ; in the <$ -flower there are generally three stamens ; the gynceceum is formed of 1-2" carpels with 1 prolonged style ; 1 pendulous ovule. The seeds are furnished with a seed-cover, which is cast off on germination. The few species (about 20) which belong to this order are marsh plants with creeping rhizome (and hence grow in clusters) ; the leaves on the aerial shoots are borne in two rows, entire, very long and linear. Sparganium (Bur-reed). The flowers are borne in globose capitula ; the perianth distinct, generally consisting of 3 small scales ; pistil bi-carpellate. Drupe, dry and woody. The stalk of the- lower $ capitula is sometimes united with the main axis, and consequently the- capitula are situated high above their subtending-leaf. SPADICIFLOEJ;. 303 Typha (Bulrush, Reed-mace) has a long, cylindrical, brown spike, the lower portion bearing ? -flowers, and the upper -flowers, which is divided into joints by alternate leaves. The ? -flowers have 1 carpel. The perianth is wanting, represented by a number of fine, irregularly-placed hairs ; pistil unicarpellate. Fruit a nut. The two genera, according to some, are related to the 2nd order In both genera native species are found. The pollination is effected by the wind, and consequently the anthers project considerably, and the stigma is large and hairy. Typha is protandrous, Sparganium protogynous. The small, fine hairs surrounding the nut of Typha assist in its distribution by the wind. Fossil Tijphas in the Tertiary. Order 5. Araceae (Arums). The flowers are small, and always borne without bracts or bracteoles on an unbranched, often very fleshy spike, which is enclosed by a spathe, often petaloid and coloured (Fig. 301). The fruit is a berry. Outer integument of the seed fleshy. The leaves have generally sheath, stalk, and blade with distinctly reticulate venation ; they are chiefly cordate or sagittate- (Fig. 302), seldom long with parallel venation as in the other Monocotyledons (Acorus, Fig. 300). The Aracese are quite glabrous, generally perennial herbs with tubers or rhizomes. Many have latex. For the rest the structure of these plants varies ; for example, while some have a perianth, in others it is wanting ; in some the perianth-leaves are free, in others united ; some have hermaphrodite flowers, but the majority unisexual (monoecious) ; some have free, others united stamens ; the ovules are orthotropous, anatropous, or campylotropous, erect or pendulous ; the ovary is 1-many-locular ; some have seeds with endosperm, others without. In habit there are great differences. While some, e.g. Colo- casia (Fig. 302), have a thick, more or less upright stem, with leaf-scars, but not woody, others are climbers, epiphytic, and maintain themselves firmly by means .of adventitious roots, on the stems and branches of trees, or even on steep rocks, e.g. PhUodendron ; the cordate, penninerved leaf is the most common (Fig. 302), but various branched forms appear ; the pedate leaves of Helicophyllum, Dracunculus, etc., are cymosely branched ; the leaves of Monstera deliciosa, perforated by tearing, should be noticed (the vascular bundles while ia the bud grow faster than the tissue between them, causing the latter to be torn, and the leaf perforated). With regard to the anatomical structure, the presence or absence of latex, raphides, resin-passages, groups of mucilagecells should be noted. Engler makes use of these anatomical peculiarities for a scientific arrangement of the order. A. ORONTIE&, CALAMUS-GROUP. $, hypogynous flowers of a completely formed monocotyledonons type (number in the whorls 2, 3, or 4). W. B. Acorus (A. calamus, Sweet- flag) has a regular, X 304 MONOCOTYLEDONES. 3-merous, pentacyclic flower (Fig. 300 (7, D). They are marsh-plants, with creeping rhizome, triangular stem, and long, sword-like leaves (Fig. 300 A) i the inflorescence is terminal, apparently lateral, being pushed to one side by the upright, sword-like spathe (Fig. 300 . Anthurium (Pr2 + 2, A2+2, G2); Pothos; Orontium (unilocular ovary with one ovule), etc. 'h h FIG. 300. Acorus calamus: A habit (much B D reduced) ; inflorescence C a flower ; ; diagram ; E longitudinal section of an ovary ; F an ovule. A FIG. 301. Arum maculatum. The B Bpnthe (h) in is longitudinally divided. SPADICIFLOR.3S. 305 B. CALLED. Flowers hypogynous, naked, $ . Calla (C. palustris). All flowers in the spike are fertile, or the upper ones are ; 6-9 stamens ; ovary unilocular with many basal ovules. Marsh-plants with creeping rhizome and cordate leaves. Honstera, RJiaphidophora, etc. C. AKINEJ;. Flowers monoecious, naked, <$ -flowers on the upper, ? on the lower part of the spadix. Arum (Fig. 301). The spadix terminates in a naked, club-like portion (&) ; below this is a number of sessile bodies (rudimentary flowers), with broad bases FIG. 302. Colocas-iu Boryi. -and prolonged, pointed tips (6); underneath these are the $flowers (m),each consisting only of 3-4 short stamens, which eject vermiform pollen-masses through the terminal pores ; then follow, last of all, ? -flowers (/), each of which consists of one unilocular ovary, with several ovules. Perennial herbs, tuberous, with cordate leaves. Dracunculus ; Biarum ; Arisarum ; PinrlHa (Athcrurus) tcr- nata with leaves bearing 1-2 buds. Zantedeschia cethiopica (Eichardia, Nile lily) ; $ , 2-3 stamens ; f? with 3 staminodes, 1-5-locular ovary (S. Africa.) In some genera sterile flowers are present between the $ and ? portions of the spadix (e.g. in Philodendron) ; in Ambrosinia a lateral, wing-like broadening of the axis of the spadix divides the -cavity of the spatlie into two chambers, the anterior 306 MONOCOTYLEDONES. containing one ? , nnd the posterior 8-10 $ -flowers in two series ; in some the stamens in the single c? -flowers unite and form a columnar " " synaudrium (e.g. in Iricffenbachia, Colocasia, Alocasia, Caladium, Taccarnm, ^ijngoninm). A remarkable spadix is found in Spathicarpa ; it is united for its entire length, ou one side, with the spathe, and the flowers are arranged upon it in r-iws, the 9 to the outside, and the $ in the middle (Zostera has a similar one). Pistia similarly deviates considerably, it is a floating water-plant, with hairy, round rosettes of leaves ; in it also the spathe and spadix are united ; at the base a $ -flower is borne, which consists of one unilocular ovary, and above several $ -flowers, each composed of two united stamens. BIOLOGY. The inflorescences are adapted for insect-pollination ; they are protogynous, since the viscous, almost sessile stigmas come to maturity and wither before the pollen, which is generally dehisced by apical pores, is shed ; some pollinate themselves freely by the pollen from the higher $ -flowers falling upon the $ -flowers below them, and in some it is conjectured that the pollination is effected by snails. The coloured spathe, and the naked end of the 5-padix (often coloured) of certain genera function as the coloured perianth in other orders ; during flowering a very powerful smell is often emitted. Arum maculatum is worthy .of notice ; small flies and midges creep down into the. spathe, between the sterile flowers (Fig. 301 b), which are situated where the spathe is constricted, and pointing obliquely downwards prevent the escape- of the insects ; in the meantime, the stigmas are in a condition to receive any pollen they may have brought with them ; after pollination the stigmas wither, and exude small drops of honey as a compensation to the flies for their imprisonment ; after this the anthers (m) open and shed their pollen, the sterile flowers wither, and the insects are then able to escape, and enter and pollinate other inflorescences. In many, a rise of temperature and evolution of carbonic acid takes place during flowering ; a spadix may be raised as much as 30C. above the temperature of the surrounding air. Again, under certain conditions, many species absorb such large quantities of water by their roots that water is forced out in drops from the tip of the leaf ; this may often be observed in. Zantedescliia. About 900 species in 100 genera. Home, the Tropics, especially S. America, India, and the Indian Islands, preferably in shady, damp forests growing as epiphytes upon trees, and on the banks of streams. Outside the Tropics few are found. Acorns calamus was introduced into Europe from Asia about 300 years ago ; it, however, never sets any fruit, as the pollen is unfertile. In England Arum maculatum is a very common plant; this and A. italicum are the only native species. Colocasia antiquorum comes from Polynesia and the Indian Islands, and also Alocasia macrorrhiza. Fossils in Cretaceous and Tertiary. USES. Many species have pungent, and even poisonous properties (e.g. Dieft'enbachia, Lagenandra, Arum), which are easily removed by boiling or roasting; the rhizomes of many species of Caladium, Colocasia (C. antiquoi urn, esculents etc.), are very rich in starch, and in the Tropics form an important source of food. An uncommon occurrence in the order is the highly aromatic rhizome of Acorus calamus; this contains calamus-oil and acorin which are used in perfumery. Many are ornamental plants, e.g. Zantedescliia ceilnopica (South, SPADICIFLORJ). 307 Africa), generally known as " Calla," and Monstera deliciosa species are grown in greenhouses. many other Order 6. Lemnacese (Duck- weeds). These are the most reduced form of the Spadiciflorse. They are very small, free- swimming- water-plants. The vegetative system resembles a small, leaf-like body (Fig. 303/-/), from which roots hang downwards; this branches by producing a new, similar leaf-like body, which springs from a pocket-like hollow (indicated by a dotted line in the figure) on each side of the older one, at its base (or only on one side). The branching is thus dichasial or helicoid (Fig. 303 A, where /,/'./",/" indicate shoots of 1st, 2nd, 3rd, 4th generations respectively). The leaf-like bodies are, according to Hegeluiaier, leaf-like stems, and thus Lcnma FIG. 303. T.imna,: A vegetative system ; B portion, of a plant, with flowers ; one stamen and tip of the carpel project ; the remaining portions being indicated by the dotted line. has no other leaves than the spathe and the sporophylls ; according to the investigations of Eugler they are stems whose upper portion (above the " pocket ") is a leaf, which is not sharply separated from the underlying stem-portion. The inflorescence is a very much reduced Araceous-spadix, consisting in Lemna of 1 or 2 stamens of unequal length (1-stamened <J -flowers), 1 unilocular carpel ( ? -flower), and 1 thin spathe (JB). [The same is found in Spirodela polyn-ldza, etc., whose daughter- shoots begin in addition with 1 basal-leaf. il'nlffia anliza. etc., have no roots.no spathe, and only 1 <? -flower in the inflorescence (Engler).] On the germination of the seed a portion of the testa is thrown off as a lid, so that an exit is opened for the radicle. 19 species. In stagnant fresh water, both Temp, and Tropical. In Europe the species are Lemna minor, trisulca, gibba ; Spirodela polyrrhiza, and Wolffia arrhiza, the smallest Flowering-plant. 308 MONOCOTYLEDONES. Family 4. Enantioblastse. The flowers in this family are hypogynous and have in part the general monocotyledonous type with 5 trimerous whorls completely developed in a regular hermaphrodite flower, and in part the flowers so much reduced that the type is very difficult to trace. On the one hand the family is well developed and has capitate inflorescences (Eriocaulacece) and on the other hand it is distinctly reduced (Centrolepidacece) . This family has taken its name from the fact that the ovule is not, as in the Liliifloras and nearly all other Monocotyledons, anatropous, but orthotropous, so that the embryo (ftXa-a-rrf) becomes placed at the end of the seed opposite (evavrtbs) to the hilum. Large, mealy endosperm. The orders belonging to this family are by certain authors grouped with the Bromeliacece and Pontederiacece, etc., into one family, FARINOSE, so named on account of the mealy endosperm, the distinguishing character of the Liliifloros then being that the endosperm is fleshy and horny. Order 1. Commelinaceae. The complete Liliaceous structure without great reductions in the number of whorls, but with generally few ovules in each loculus of the ovary, is found in the CommelinaceEe, an almost exclusively tropical order with about 317 species ; herbs, some of which are introduced into our gardens and greenhouses. The stems are nodose ; the leaves often clasp- ing ; the flowers are arranged in unipared scorpioid cymes, often so that they form a zig-zag series falling in the median line of the bracts, and after flowering they bend regularly to the right or left, outwards or inwards. They are more or less zt/gomorphic, particularly in the stamens, which in the same flower are of different forms or partially suppressed. The outer series of the perianth is sepaloid, the inner petaloid, generally violet or blue ; the filaments are some- times clothed with hairs formed of rows of bead-like cells (well known for showing protoplasmic movements). Fruit a trilocular capsule with loculicidal dehiscence (generally few-seeded) ; in some a nut. The radicle is covered by an external, warty, projecting covering which is cast off on germination. The abundant rapliides lie in elongated cells whose transverse walls they perforate. Commelina, Tradtscantia, Tinnantia, Cyanotis, Dichorisandra. Order 2. Mayacaceae. This order is closely allied to the Commelinaceae. 7 species. American marsh- or water-plants. In many of the following orders of this family the flowers are united into compound inflorescences, with which is accompanied a reduction in the flower. Order 3. Xyridaceae (50 species). Marsh-plants with radical, often equit- ant leaves arranged in 2 rows, and short spikes on long (twisted) stalks. The flowers, as in the Commelinacere, have sepals (which however are more chaffy) and petals, but the outer series of stamens is wanting. Capsule (generally many-seeded). Order 4. Rapateacese. Marsh-plants with radical leaves, usually in two LILIIFLOR.E. 809 rows, and several spikelets on the summit of the main axis, clustered into a capitulum or unilateral spike. Each spikelet has numerous imbricate floral- leaves and one flower. 24 species. South America. ' Order 5. Eriocaulaceae. The " Composite among Monocotyledons," a tropical order. The flowers are borne in a capitulum surrounded by an involucre, very similar to that of the Compositae. The flowers are very small, unisexual, $ and often mixed indiscriminately in the same capitulum ; they have the usual pentacyclic structure ; the leaves of the inner perianth are often connate and more membranous than the outer ; in some the outer series of stamens are suppressed ; in each of the 3 loculi is one pendulous ovule. Capsule. The leaves are generally radical and grass-like. 335 species ; Eriocaulon, Paepa- lanthus, etc.,