Mistletoe is the only representative of this Family of woody parasites in Britain, which in the tropics are numerous, including many species with large and brilliant flowers.

OBSERVE a cross section through the attachment of Mistletoe to its stock; it shows the intimate union, without intermingling, of the tissues of parasite and prey: the viscous tissue of the ripe pericarp, which secures the adhesion of the seed to the bark of trees when conveyed by birds. In germinating the radicle penetrates the bark, forming a kind of rhizomatous root, which applies itself to the young alburnum of the stock, preying upon the ascending sap, which is further elaborated in the leaves of the Mistletoe. Observe, also, the anthers, adherent to the lobes of the perianth, and dehiscing by pores.

The structure of the inferior ovary of the Order has been much misunderstood. If cut across, there is no cavity containing an ovule to be seen. This is owing to the circumstance that the sides of the ovary are adherent to the solitary, erect, naked ovule, so that no distinction between ovary and ovule is apparent. The albuminous seeds frequently contain 2 or more embryos, as is also usually the case with the exalbuminous seeds of the Orange.

Mistletoe grows upon trees belonging to very different Natural Orders; in Britain, chiefly upon the Apple,

Thorn, Maple, and Lime. It rarely occurs upon the

Oak.

32. Natural Order-Cornaceæ.

The Cornel Family.

DISTRIBUTION. Widely dispersed in both hemispheres. One British genus, species 2.

Shrubs or herbs. Corolla epigynous, regular. Ovary

2-celled.

Type-Common Cornel (Cornus sanguinea).

A deciduous shrub, with opposite entire leaves, and small white cymose flowers.

OBSERVE the white involucral bracts of Dwarf Cornel (Cornus suecica) and of C. florida, the latter an American species. The involucres give the small flower-heads the appearance of single flowers.

Division Gamopetala (Corolliflora).

33. Natural Order-Caprifoliaceae. The Honeysuckle Family.

DISTRIBUTION.-Chiefly in temperate and sub-tropical regions of both hemispheres.-British genera 5, species 8. Shrubs or herbs. Corolla epigynous. Stamens epipetalous. Ovary 3-5-celled.

Type-Common Honeysuckle (Lonicera Periclymenum).

A woody climber, with opposite entire leaves, and terminal heads of fragrant irregular flowers.

OBSERVE the thick cellular pith of Elder (Sambucus nigra), useful for pith-balls for electrical experiments, and the cylinder of wood, after the pith is removed, for popguns. Observe, also, the enlarged lobes of the corolla in cultivated varieties of Guelder Rose (Viburnum Opulus). In the wild form, the outer flowers only of the cymes are enlarged in this way, at the expense of the essential organs: they are barren or neuter, in consequence.

Observe, also, Tuberous Moscatel (Adoxa moschatellina), a low, tender herb, with small capitate flowers, of which the upper one of each head has 4, and the four lateral flowers each 5, stamens. The stamens are branched, and each branch bears one lobe of the anther, so that the flowers appear to be octandrous or decandrous. Compare the neuter flowers of Guelder Rose and Hydrangea in the former the lobes of the corolla, in the latter the lobes of the calyx, are enlarged.

:

Linnæa borealis, a small creeping wiry evergreen, with pretty pendulous flowers, native of Scotland, and common in the North of Europe, is named after Linnæus, who is represented in his portraits with a sprig of this plant in his button-hole.

34. Natural Order-Rubiacea. Tribe Stellatæ. The Stellate Tribe of the Madder Family.

DISTRIBUTION.-Dispersed through temperate regions of both hemispheres; less numerous between the tropics, where, however, typical Rubiaceæ abound. British genera 4, species 14.

Herbs. Leaves verticillate.

Corolla epigynous. Stamens

epipetalous. Ovary 2-celled.

Type-Sweet Woodruff (Asperula odorata).

A perennial herb, with slender creeping rhizome, erect stem with verticillate leaves, and a terminal cyme of small white flowers.

All British Rubiaceæ belong to the Tribe Stellatæ, characterised by the leaves in whorls. The more typical members of the Order abound in tropical countries, where many species are amongst the commonest weeds. Others, however, are highly ornamental, and are cultivated in our plant-houses. A few species are of great economic importance, especially the Coffee shrub (Coffea arabica) a native of Eastern Tropical Africa, but cultivated very extensively in Ceylon, the East and West Indian Islands, and Brazil. The seeds are contained, two together, in a fruit of about the size and colour of a Cherry. The pulp of the pericarp is removed by washing and mechanical contrivance, leaving the parchment

like endocarp immediately enclosing the seeds to be separated in a rolling-mill.

In 1877 upwards of one million six hundred thousand cwts. of Coffee were imported, seven hundred and eighty thousand being from Ceylon alone. More than two hundred and ninety thousand cwts. were entered for home consumption.

Other important exotic species are the Quinine-producing Cinchonas or Peruvian barks, natives of the Andes of Peru, and now introduced into British India and Java Ipecacuanha, the emetic root of Cephaëlis Ipecacuanha: and Rubia tinctorum, a plant of the Levant and Southern Europe, cultivated in France for the sake of its rhizome, which affords the valuable dye, Madder. Upwards of 283,000 cwts. of Madder and Garancine (the latter prepared from Madder by the action of sul