Part 66

FIG. 479.--Diagram of the position of leaf and tendrils. The branch is divided into sections on the sympodial theory (the successive generations, I, II, III, IV, are alternately white and shaded); k buds.

FIG. 480.--A Flower throwing off the corolla; B flower after the removal of the corolla; C, D longitudinal and transverse section of seed; E longitudinal section of gynœceum; s calyx.

FIG. 481.--Diagram of branch and position of leaves; sl tendril; lt the main axis; ax stipules of the foliage-leaf shown below; g axillary-bud (the dwarf-branch); v its fore-leaf; l{1} l{2} its first two foliage-leaves with their stipules; lt{1} long-branch in the axil of v (everything appertaining to this branch is entirely black); v{1} the first leaf of this branch.]

Vitis and Ampelopsis (5-merous flowers); Cissus (4-merous flower); Leea (without stipules, corolla gamopetalous). The inflorescence in Pterisanthes (E. Ind.) has a peculiar, flat, leaf-like axis, on the edges of which ♂-flowers are borne, and on the surface ♀-flowers.

The TENDRILS in Ampelidaceæ are modified branches, since they bear leaves and may be abnormally developed as branches with foliage-leaves, and finally the inflorescences are borne in the position of the tendrils, and tendrils are met with which are partly inflorescences. The explanation of the position of the tendril, namely, right opposite the foliage-leaf but without a subtending-leaf, has been much disputed. The relative positions are as follows: in Vitis vinifera the following two kinds of shoots and relative positions are found (the other species deviate in one or other particular), (a) LONG-BRANCHES, which have 2 scale-leaves and a large number of foliage-leaves with a divergence of 1/2; opposite the lowest 3–5 foliage-leaves no tendrils are found, then follow: 2 foliage-leaves with tendrils, 1 without a tendril, 2 with and 1 without, etc., with great regularity. Buds are developed in the axils of the foliage-leaves (Fig. 479): these develop into (b) DWARF-BRANCHES, which commence with 1 laterally-placed scale-leaf (fore-leaf; Fig. 481 v) succeeded by several foliage-leaves with a divergence of 1/2 (in a plane at right angles to that of the mother-shoot), but the whole shoot is extremely small, and often dries up and drops off in the autumn, so that only the scale-leaf, v, with the bud (Fig. 481 lt{1}) in its axil remains. This bud in the following year developes into a new long-branch, and since its leaves lie in a plane at right angles to that of the dwarf-branch, their plane coincides with that of the long-branch from which it is developed (the grandmother axis).--The tendrils no doubt may most correctly be regarded as the modified main axis which has been pushed aside by a lateral branch. The branches are then sympodia, whose successive shoots bear alternately 1 and 2 foliage-leaves: thus, on the figure there are portions altogether of 5 shoots (I.-V.), the 1-leaved ones are shaded, the 2-leaved ones are white. The following facts however are adverse to this theory: (1) the first leaf on an axillary bud is then situated 180° from the subtending leaf (e.g. the lowermost shaded leaf, Fig. 479, 180° from the lowermost white leaf), whilst the rule in the Dicotyledons is that it is placed only about 90° to one side. (2) The buds (Fig. 479 K) from which the dwarf-branches develop, must then be accessory and sister-buds to the sympodial shoots, but their first leaves have a different relative position to this, which is very peculiar, and a still more remarkable fact is that the buds, K, etc. are similar in structure and present in all the axils; thus we only_ find accessory buds in the cases where no tendrils are opposite to the leaves, and the main bud must then be considered to be suppressed. (3) The development proves that the tendrils arise on the side of a vigorous growing-point of the stem or by its division, and do not develop, as might be expected, from the apex of the shoot. But these relations however, find their analogues and are all capable of explanation, whereas other less natural modes of explanation are opposed to them.

435 species; especially in the Tropics; they are rarer in America. In N. Am. some Vitis-species and Ampelopsis quinquefolia are found. Vitis vinifera is supposed to have originated in the districts East and South of the Caspian Sea. Wine is obtained from Vitis-species, especially V. vinifera, and “raisins,”--(the name “currants,” given to a special variety with small, seedless fruits, is derived from Corinth).--The species of Ampelopsis (Virginian Creeper) are cultivated as ornamental plants.

Order 5. =Rhamnaceæ.= The stamens are placed opposite the petals as in the Ampelidaceæ (Fig. 482), but the flowers are much more perigynous or entirely epigynous. The trees and shrubs belonging to this order have simple, most frequently penninerved leaves with stipules; frequently thorny (modified branches). The flowers are inconspicuous, sometimes unisexual (Fig. 482), and have 5 (-4) sepals, petals, stamens, and generally 3 (2–5) carpels. The calyx has valvate æstivation. The petals are very small (generally less than the sepals), often spoon-like, hollow, and embracing the stamens; a disc covers the inner surface of the thalamus or the base of the style in the epigynous flower; gynœceum simple, with one style and one erect ovule in each loculus. The fruit is most frequently a drupe. The embryo is large, often green or yellow, with endosperm.

Rhamnus (Buckthorn) has a juicy drupe with 3 (2–4) stones, surrounded at the base by the persistent portion of the receptacle; the disc is thin. R. cathartica (common Buckthorn): diœcious, with opposite, serrate leaves. R. frangula (Alder Buckthorn): flowers ☿, with scattered, entire leaves.--~Ceanothus (N. Am., with richly-flowered inflorescences and a fruit closely resembling that of the Euphorbias). Phylica, Pomaderris (Austr., fruit a capsule). Zizyphus, Paliurus, Colletia (S. Am.) are thorny shrubs; C. spinosa has thorny shoots with small, caducous leaves; the seedling has normal foliage-leaves. Others climb by tendrils as in the Ampelidaceæ, e.g. Gouania.~

475 species, 40 genera; chiefly in temperate and tropical climes. Some are medicinal plants, the bark and fruit having purgative properties (the bark of Rhamnus frangula and “Cascara Sagrada” from the bark of R. purshiana are officinal). The fruits and seeds of others are edible, for example, the fruits of Zizyphus lotus, Z. vulgaris, Z. spina Christi, etc. Green and yellow dyes are obtained from the fruit of R. cathartica, infectoria and others (Avignon grain). Ceanothus-, Rhamnus- and evergreen Phylica-species are ornamental shrubs.

Family 18. =Thymelæinæ.=

Exclusively trees or shrubs with simple, entire, scattered leaves without stipules. They have a strongly perigynous, regular, 4-merous flower. The receptacle (often coloured) envelopes a simple gynœceum formed of =1= carpel and with, in most cases, =1= ovule, bearing on its edge 4 (or 5) petaloid sepals and, but rarely at the same time, small, scale-like petals. The corolla is most frequently entirely wanting (and hence these plants were formerly reckoned among the Monochlamydeæ); frequently only one of the 2 whorls of stamens, which are situated on the inner side of the edge of the receptacle, is developed. The fruit is most frequently a 1-seeded berry or drupe, or a nut which may be falsely berry-like, the partly persistent receptacle being fleshy and enveloping it.

This family appears the most nearly allied to the Frangulinæ, especially the Rhamnaceæ, and may be considered as a further development of these in the direction of the petaloid development of the receptacle and reduction of the corolla and gynœceum, which in this instance only consists of one carpel. Another deviation is that both the whorls of stamens are present, while one of these is always wanting in Frangulinæ. They also appear to be related to the Lauraceæ (see page 391).

Order 1. =Thymelæaceæ.= The flowers are most frequently ☿ (Fig. 483). The receptacle is high, generally tubular, coloured, and bears on its edge the 4-(or 5)-merous calyx, with imbricate æstivation. The corolla is wanting or is represented by small scales. The stamens are situated on the inside of the receptacle, and number 4 + 4 (or 5 + 5); stigma capitate. 1 pendulous ovule (Fig. 483 B), the radicle pointing upwards. The fruit is most frequently a berry. ~A disc is sometimes developed. Endosperm wanting or very slight.~

Daphne (Spurge-Laurel, Fig. 483) has a deciduous receptacle, often coloured; sepals 4; petals absent; stamens 4 + 4. Berry.--Gnidia (corolla); Pimelea (2 stamens); Thymelæa; Passerina and others.

400 species; chiefly in the warm, sub-tropical zone, especially the Cape and Australia. Only Daphne and Thymelæa in Europe. In the fruit and bark of some, for example Daphne, pungent, burning and poisonous properties are found. The bark of D. mezereum (native and cultivated) and D. laureola is officinal. A specially tough bast is found in some species, for example Lagetta lintearia (Lace-tree, Jamaica), which is used in weaving. Some are cultivated in gardens as ornamental shrubs, especially species of Daphne.

Order 2. =Elæagnaceæ.= Shrubs or trees, which are easily recognised by the covering of peltate hairs found upon almost all parts of the plant, causing them to assume a silvery or rusty-brown appearance. Stipules are absent; the leaves are simple, most frequently scattered. Flowers (Figs. 484, 485) frequently unisexual. The sepals are valvate, 2-4; the corolla is wanting; stamens 4 + 4 or 0 + 4. The ovule is erect and the radicle turned downwards (Fig. 486). The fruit is a nut, but becomes a false fruit, being surrounded by the persistent receptacle or the lower part of it, and thus assuming a berry- or drupe-like appearance (Fig. 486). Endosperm insignificant.--Shepherdia (opposite leaves) has 4 sepals, 4+4 stamens, as in Daphne. Diœcious.--Elæagnus (Silver-leaf) is ☿, has 4–6 sepals, and 4–6 stamens alternating with them. Hippophaë is diœcious; it has 2 sepals and 4 stamens in the ♂-flower (perhaps properly speaking 2+2 stamens); thorny (stem-structures).

16 species; especially ornamental shrubs, e.g. Elæagnus argentea, angustifolia; Hippophaë rhamnoides and Shepherdia canadensis. Northern Temp.

FIG. 484.--Floral diagram.

FIG. 485.--Longitudinal section through the flower.

FIG. 486.--Longitudinal section through the fruit.]

Order 3 (?). =Proteaceæ.= This order has its chief centre in the dry regions of Australia (6/10–7/10 of about 1,000 species), a smaller number in S. Africa (2/10–3/10). a few species in S. Am. Trees or shrubs, leaves generally scattered, without stipules, and more or less dry, leathery, evergreen, and often of very different forms on the same plant (undivided, compound, etc.) The flowers are ☿ (rarely unisexual), and 4-merous in the single, petaloid perianth and in the staminal whorl; 1 carpel; sometimes zygomorphic. The perianth-leaves are generally almost free, with valvate, æstivation, often leathery. Small scales alternating with the perianth are often found at the base of the ovary. The stamens generally have extremely short filaments, and are situated opposite, sometimes quite on the tip of the perianth-leaves, in a spoon-like groove. The gynœceum is 1-locular, has 1–several ovules, and is often raised on a stalk-like internode. The fruit is a follicle or nut. The seeds, most frequently winged, have no endosperm.--Protea, Manglesia, Hakea, Banksia, Grevillea, etc. 50 genera; about 1,000 species. Several species are cultivated in our conservatories for the sake of the flowers, which are beautifully coloured and arranged in crowded inflorescences. Protandrous. It is doubtful whether they were existent in Europe in the Tertiary Period. The true systematic position of the order is doubtful. They are related to the Leguminosæ and Rosifloræ, but more closely no doubt to the two preceding orders.

Family 19. =Saxifraginæ.=

The flower is generally perfect, regular and polypetalous, usually perigynous or epigynous, eucyclic and 5-merous; most frequently S5, P5, A5 + 5 or 5 + 0 and G=2=-5, but other numbers are found, especially 4; the flowers are very frequently obdiplostemonous. The calyx is sometimes large and the corolla small; the carpels in some are entirely free, in others more or less united. Endosperm is found in the majority. ~The hypogynous forms approach the Cistifloræ, the others the following families, especially the Rosifloræ. This family is not, upon the whole, so well defined and natural as most of the others. The Saxifragaceæ proper, approach very near to the Rosaceæ, especially Spiræa, and form a transition to it. The forms with opposite leaves, as Philadelphus, etc., approach the Myrtifloræ, just as the Escalloniæ appear to be closely allied to Bicornes, especially Vacciniaceæ. Finally through Pittosporaceæ, they pass over to the Frangulinæ. The family terminates in very reduced forms, on the one hand in the arborescent orders with crowded inflorescences, on the other perhaps in the very remarkable order Podostemaceæ.~

Order 1. =Crassulaceæ.= Nearly all are herbs or small shrubs with round, succulent branches and scattered, fleshy, often more or less round leaves, which are very rarely incised, and never have stipules. The flowers are generally borne in dichasia or unipared scorpioid cymes, which again may be arranged in racemes, umbels, etc.; they are regular, ☿, hypogynous or perigynous, and most frequently have free sepals and petals (gamopetalous corollas with sessile stamens are found in Cotyledon, Bryophyllum, Echeveria, and others); the floral formula is Sn, Pn, An + n, Gn, where n may have very different values, partly depending upon the size of the flower (e.g. 4–7 in Sedum, Fig. 487; 6–30 in Sempervivum; 4 in Rhodiola, Bryophyllum, and Kalanchoë; 5 in Echeveria, Umbilicus, Cotyledon). The carpels are free and are placed opposite the petals (Fig. 487). Fruit a syncarp composed of follicles containing many, small seeds without endosperm. Outside each carpel is found a small, nectariferous scale (Fig. 487). ~The northern genus, Rhodiola, is diœcious. The petal-stamens are wanting in some (Crassula, Bulliarda, and others). The floral-leaves are very often displaced upon their axillary branches. A multicarpellary gynœceum also occurs.~

Sedum (Stonecrop) is generally 5-merous with 10 stamens; Sempervivum tectorum (House-leek), 12-merous, and with 24 stamens. ~The leaves of Bryophyllum calycinum very readily form buds, and also frequently exude water from the edges.~

485 species; especially Temp. (Cape, Europe). Principally used as ornamental plants.

Order 2. =Saxifragaceæ.= The flowers are 4–5-merous with =2= (-3) carpels, most frequently: S5, P5, A5 + 5 (obdiplostemonous), G2. They are regular, ☿, polypetalous, hypogynous, perigynous or most frequently more or less epigynous (Fig. 488). The carpels may be individually quite free, but are more frequently united at the base, or the entire portion enclosing the ovules is united into a 1- or 2-locular ovary, the styles, however, are always free. Fruit a capsule with many seeds; endosperm present.--They are herbs, most frequently with scattered leaves without stipules; but the leaf-base is broad. The inflorescences are most frequently cymose, and a displacement of the floral-leaves is frequent (e.g. Chrysosplenium).--~Some Saxifraga-species, e.g. S. sarmentosa, have irregular flower with an oblique plane of symmetry. The petal-stamens in some may be wanting: Heuchera, species of Saxifraga and Mitella. The corolla is wanting in others.~

Saxifraga (Saxifrage): S5, P5, A5 + 5, G2 (Fig. 488); capsule bilocular, opening along the ventral suture between the 2 persistent styles. ~S. granulata has small tubers at the base of the stem.~--Chrysosplenium (Golden Saxifrage): 4 sepals, no corolla, 4 + 4 stamens; 1-locular capsule.