Martynia.—­Handsome half-hardy, fragrant annuals.  The seed should be sown on a hotbed in March.  When the plants are sufficiently advanced transplant them singly into pots of light, rich earth, and keep them in the stove or greenhouse, where they will flower in June.  Height, 11/2 ft.

Marvel of Peru (Mirabilis).—­Half-hardy perennials, which are very handsome when in flower, and adorn equally the greenhouse or the open.  They may be increased by seed sown in light soil in July or August and planted out in the border in spring.  At the approach of frost take the roots up and store them in dry ashes or sand.  They flower in July.  Height, 2 ft.

Massonia.—­Singular plants, which to grow to perfection should be placed in a mixture of loam, peat, and sand.  They require no water while in a dormant state, and may be increased by seed or by off-sets from the bulbs.  Height, 3 in. to 6 in.

Mathiola.—­See “Stocks.”

Mathiola Bicornis (Night-scented Stocks).—­A favourite hardy annual whose lilac flowers are fragrant towards evening.  They may be grown from seed sown between February and May on any ordinary soil.  Height, 1 ft.

Matricaria.—­This is a half-hardy annual of little interest so far as its flowers are concerned, and is mostly grown as a foliage plant.  The seed should be sown in a frame in March, and transplanted at the end of May.  Height, 1 ft.

Maurandia Barclayana.—­This elegant twining plant is best grown in pots, so that it can more conveniently be taken indoors in the winter.  The soil should be light and rich.  Cuttings can be taken either in spring or autumn, or it may be raised from seed.  It does very well in the open during the summer, placed against a wall or trellis-work, but will not stand the cold.  In the greenhouse it reaches perfection, and blooms in July.  Height, 10 ft.

Mazus Pumilio.—­A pretty diminutive herbaceous plant.  When grown in peat and sand in an open situation it survives from year to year, but it will not live through the winter in cold clay soils.  Its pale green foliage is seen to advantage in carpet bedding, and its branched violet flowers, put forth from June to September, make it a desirable rock-work plant.  It may be increased by transplanting, at the end of April, the rooted stems which run under the surface of the ground.

Meconopsis Cambrica(Welsh Poppy).—­An ornamental hardy perennial, often found on English rocks.  It may be grown in any light, rich soil, is easily raised from seed, and blooms in June.  Height, 1-1/2 ft.

Medlars.—­These trees will grow on any well-drained soil.  The Dutch Medlar is most prized, as it bears the largest fruit.  It is raised from seed, and usually trained to a standard form.  The Nottingham and Royal are also excellent varieties.  Any special variety may be grafted on to the seedlings.  On deep soils it is best grafted on the Pear stock; on light, sandy soil it may be grafted on the White Thorn.  No pruning is required, beyond cutting away cross-growing branches.