The contrast presented by the physiognomy of the Casuarineas, acicular-leaved trees, and the almost leafless Peruvian Colletias and Pothos plants (Aroideas), is still more striking when we compare these types of extreme contraction in the leaf form with Nymphæaceæ and Nelumboneæ. Here we again meet, as in the Aroideæ, with leaves in which the cellular tissue is excessively expanded upon long, fleshy, succulent petioles,—as Nymphæa alba, N. lutea, N. thermalis (formerly called N. lotus, from the hot spring of Pecze, near Groswardein in Hungary), the species of Nelumbo, Euryale amazonica (Pöppig), and Victoria Regina, allied to the prickly Euryale, although of a very different genus, according to Lindley, and discovered in 1837 by Sir Robert Schomburgk in the river Berbice, in British Guiana. The round leaves of this splendid aquatic plant are from 5 to 6 feet in diameter, and surrounded by upright margins from 3 to 5 inches in height, which are light green on the inner side, but of a bright crimson on the outside. These agreeably perfumed flowers, of which 20 or 30 may be seen together in a small space, are about 15 inches in diameter, of a white or rose colour, and have many hundred petals.[[QA]] Pöppig also gives to the leaves of his Euryale amazonica, which he found at Tefé, a diameter of about 6 feet.[[QB]] Whilst Euryale and Victoria present a greater parenchymatous expansion of the leaf-form in all its dimensions than other genera, the most gigantic development of the blossoms occurs in a parasitical Cytinea, which Dr. Arnold discovered in Sumatra in 1818. This flower, Rafflesia Arnoldi (R. Brown), has a stemless blossom measuring three feet in diameter, surrounded by large leaf-like scales. Like funguses, it has an animal odour, and smells something like beef.
[95]. p. 227—“Lianes, Creeping Plants, (Span. Vejuccos.)”
According to Kunth’s division of Bauhinias, the true genus Bauhinia belongs to the New Continent. The African Bauhinia, B. rufescens (Lam.), is a Pauletia (Cav.), a genus of which we also discovered some new species in South America. In the same manner the Banisterias of the Malpighiaceæ are actually an American form. Two species are indigenous to the East Indies, and one—described by Cavanilles as B. leona—to Western Africa. In the tropical zone, and in the Southern hemisphere, species of the most different families belong to the climbing plants which in those regions render the forests so impenetrable to man and so accessible and habitable to the whole monkey family (Quadrumana), the Cercoleptes, and the small tiger cats. The Lianes thus afford whole flocks of gregarious animals an easy means of rapidly ascending high trees, passing from one tree to another, and even of crossing brooks and rivulets.
In the south of Europe and in the north of America, Hops from the Urticeæ, and the species of Vitis from the Ampelideæ, belong to Climbing Plants; while this form is represented in the tropics by climbing and trailing grasses. We found on the elevated plains of Bogota, in the pass of Quindiu in the Andes, and in the Cinchona forests of Loxa, a Bambusa allied to Nastus, our Chusquea scandens, twined round powerful trunks of trees, adorned at the same time with flowering Orchideæ. Bambusa scandens (Tjankorreh), which Blume found in Java, belongs probably to Nastus, or to the grass-genus Chusquea, the Carrizo of the Spanish settlers. In the pine forests of Mexico, Climbing Plants seem to be entirely wanting; but in New Zealand a fragrant Pandanus, Freycinetia Banksii, together with one of the Smilaceæ, Ripogonum parviflorum (R. Brown), which renders the forests almost impenetrable, winds round a gigantic fir-tree more than 200 feet high, Podocarpus dacryoides (Rich.), called Kakikatea in the language of the country.[[QC]]
A striking contrast to these Climbing Grasses and Creeping Pandaneas is afforded by the splendid many-coloured blossoms of the Passion flowers (among which, however, we ourselves found one arborescent, upright, species (Passiflora glauca) in the Andes of Popayan, at an elevation of nearly 10,500 feet, and by the Bignoniaceæ, Mutisiæ, Alströmeriæ, Urvilleæ, and Aristolochiæ. Among the latter, our Aristolochia cordata has a coloured (purplish red) calyx, about seventeen inches in diameter; “flores gigantei, pueris mitræ instar inservientes.” Owing to the quadrangular form of their stalks, their flattening, which is not occasioned by any external pressure, and a band-like undulatory motion, many of these climbing plants have a peculiar physiognomy. The diagonal intersections of the stems of Bignonias and Banisterias form, by means of furrows in the ligneous substance, and through its clefts, where the bark penetrates to some depth, cruciform or mosaic-like figures.[[QD]]
[96]. p. 228—“The form of Aloes.”
To this group of plants, which is characterised by a great similarity, belong Yucca aloifolia, which penetrates as far north as Florida and South Carolina; Y. angustifolia (Nutt.), which advances to the banks of the Missouri; Aletris arborea; the Dragon-tree of the Canaries, and two other Dracænas belonging to New Zealand; arborescent Euphorbias; and Aloe dichotoma, Linn., (formerly the genus Rhipidodendrum of Willdenow), the celebrated Koker-boom, whose stem is four feet in thickness, about twenty feet high, and has a crown measuring 426 feet round.[[QE]] The forms which I have here associated together belong to very different families: as, for instance, to the Liliaceæ, Asphodeleæ, Pandaneæ, Amaryllideæ, and Euphorbiaceæ; and are therefore, with the exception of the last named, all included under the great division of Monocotyledons. One of the Pandaneæ, Phytelephas macrocarpa (Ruiz), which we found on the banks of the Magdalena river in New Granada, exactly resembles with its feathery leaves a small palm-tree. The Tagua (as it is called by the Indians) is moreover, as Kunth has observed, the only Pandanea of the New Continent. The singular Agave-like and high-stemmed Doryanthes excelsa of New South Wales, which the intelligent Correa de Serra was the first to describe, belongs to the Amaryllideæ, like our low-growing Narcissuses and Jonquils.
In the candelabra-like form of Aloes, the branches of the main-trunk must not be confounded with the flower-stalks. In the American aloe, Agave Americana (Maguey de Cocuyza), which is entirely wanting in Chili, and in the Yucca acaulis (Maguey de Cocuyza), the leaf-stalks present a candelabra-like arrangement of the blossoms during the excessively rapid and gigantic development of the inflorescence, which, as is well known, is but too transient a phenomenon. In some arborescent Euphorbias the physiognomical character depends, however, on the branches and their arrangement. Lichtenstein describes,[[QF]] with much animation, the impression made upon him by the appearance of an Euphorbia officinarum which he saw in the “Chamtoos Rivier,” near Cape Town. The form of the tree was so symmetrical, that it repeated itself on a small scale, like a candelabrum, to a height of more than 30 feet. All the branches were furnished with sharp thorns.
Palms, Yucca and Aloe plants, arborescent Ferns, some Aralias, and the Theophrasta, where I have seen it in a state of luxuriant growth, present to the eye a certain physiognomical resemblance of character by the nakedness of the stems (there being no branches) and the beauty of their summits or crowns, however they may otherwise differ in the structure of the inflorescence.
Melanoselinum decipiens, (Hofm.), which has been introduced into our gardens from Madeira, and is sometimes from 10 to 12 feet high, belongs to a peculiar group of arborescent umbelliferæ allied to the Araliaceæ, to which other species, as yet undiscovered, will undoubtedly at some future time be added. Ferula, Heracleum, and Thapsia likewise attain a considerable height, but they are still herbaceous shrubs. Melanoselinum stands almost entirely alone as an arborescent umbelliferous plant; Bupleurum (Tenoria) fruticosum, Linn., of the shores of the Mediterranean, Bubon galbanum of the Cape, and Crithmum maritimum of our sea-coasts, are only shrubs. Tropical countries, where, as Adanson long since very correctly remarked, Umbellifereæ and Crucifereæ are almost wholly wanting in the plains, exhibit, as we ourselves observed, the most dwarfish of all the umbelliferous family on the lofty mountain ridges of the South American and Mexican Andes. Among the thirty-eight species which we collected on elevations whose mean temperature was below 54°.5 Fahr., we found Myrrhis andicola, Fragosa arctioïdes, and Pectophytum pedunculare, interspersed with an equally dwarfish Alpine Draba, growing moss-like close to the rock and the frequently frozen earth, at a height of 13,428 feet above the level of the sea. The only tropical umbelliferous plants which we found on the plain in the New Continent were two species of Hydrocotyle (H. umbellata and H. leptostachya) between the Havannah and Batabano, and therefore at the extreme limit of the torrid zone.