AN ENCYCLOPAEDIA OF HORTICULTURE. 



355 



Mertensia continued. 

 acute. Stems erect, simple, h, 6in. to 18in. 

 North America, 1801. 

 colour of its flowers, 

 white-flowered form in cultivation. 



East Asia and 



A very pretty species, varying in the 

 SYN. Pulmonaria sibirica. There is a 



FIG. 552. INFLORESCENCE AND DETACHED FLOWER OF 

 MERTENSIA VIRGINICA. 



H. virginica (Virginian).* Virginian Cowslip, fi. purple-blue, 

 tubular, about lin. long, disposed in gracefully-drooping terminal 

 clusters. Spring and summer. I. lanceolate-ovate, lower ones 

 4in. to 6in. long, 2in. to Sin. broad, shortly stalked, h. 1ft. to 2ft. 

 Virginia, 1799. See Fig. 552. (B. M. 160, under name of Pvinw- 



MERTENSIA (of Willdenow). Included under 



Gleichenia. 



MEK.ULIUS LACRYMANS. This is often called 

 the Dry-rot Fungus. It is the most frequent cause, 

 though not the only one, of the form of decay in the 

 woodwork of houses and of greenhouses commonly known 

 as Dry-rot. The wood is traversed in every direction by 

 the thread-like cells (mycelium) of the fungus; and the 

 tissue is thereby so altered in its nature as to crumble 

 readily on pressure. Merulius attracts moisture, and is 

 constantly damp. It spreads over large surfaces in dark, 

 ill- ventilated spaces, when in the spore-producing stage, 

 and its surface (hymenium) is then marked with pores, 

 or small tubes. 



Remedies. The remedies employed for the attacks of 

 this fungus (which, if unchecked, proves most destruc- 

 tive in houses, as it spreads rapidly) are, where possible, 

 soaking the woodwork with strong solutions of corrosive 

 sublimate, or of copper sulphate. Since well-dried or 

 seasoned wood is far less liable to be attacked, such 

 wood alone should be used in house -building. Good ven- 

 tilation, to insure the dryness of the woodwork in the 

 house, is an essential means for the prevention of Dry-rot. 



MERYTA (said to be derived from meryo, to roll 

 up ; in reference to the male flowers forming something 

 like a rolled-up ball). SYN. Botryodendron. OBD. 

 AraliacecB. A genus comprising six species of stove or 

 greenhouse, glabrous trees, natives of Norfolk Island, 

 New Zealand, and the South Pacific Islands. Flowers 

 dioecious, in panicled heads, at the sides of the branches, 

 or in sessile fascicles ; males small ; females large. 

 Leaves simple, large, entire or sinuated. For culture, 

 see Aralia. 

 M. latlfolia (broad-leaved). /. greenish-yellow, male, female, 



and hermaphrodite, densely crowded into oblong compound 



heads, which are 2in. to Sin. long, formed of innumerable clusters 



of about six sessile flowers, on a thick green rachis. March. 



I. 2ft. to 3ft. long, crowded, narrow-obovate or fiddle-shaped ; 



Eetiole short, stout, h. 50ft. to 60ft. Norfolk Island. Green- 

 ouse. (B. M.5932.) 



M. sonchifolia(Sonchus-leaved). I. lyrate-pinnatisect ; terminal 

 lobe deltoid or somewhat acuminate ; side lobes rhomboid-ovate, 

 acute ; margins irregularly toothed, dark green, marked with 

 numerous whitish spots. Stem (and petioles) olive-green. New 

 Caledonia, 1879. Stove. (I. H. 1879, 340.) 

 MESEMBRYANTHEMTTM (from mesembria, 



midday, and antnemon, a flower ; in reference to the 



flowers opening better on sunny days). Fig Marigold. 



OBD. FicoidecB. A very extensive genus (about 300 



Mesembryanthemum continued. 



species) of greenhouse, or rarely hardy, erect or pros- 

 trate, fleshy, leafy herbs or sub-shrubs, mostly natives 

 of South Africa, a few being found in other parts of 

 Africa, and in Australia, New Zealand, the Canary 

 Islands, the Mediterranean region, and Arabia. Flowers 

 white, yellow, or different shades of red, &c., conspicuous, 

 axillary or terminal, cymose, paniculate, or corymbose ; 

 calyx tube adnate with the ovary; lobes five, rarely 

 one to eight, unequal, herbaceous or scariose ; petals 

 many, one to many-seriate, inserted in the calyx tube, 

 linear. Capsules tightly closed during dry weather, 

 and opening naturally after rain (if placed in water 

 until thoroughly soaked, and then removed, an old 

 capsule will open out its carpellary valves, radiating 

 from the centre, like a star, and will close them again 

 when dry; this may be repeated several times without 

 destroying its remarkable hygroscopic property). Leaves 

 often opposite, thick, fleshy, very variable in shape, entire 

 or furnished with spiny rigid hairs on the margins. The 

 culture of most species of this genus is very simple, the 

 great secret of success consisting in exposing the plants 

 to the full sun at all times, and in not using too rich 

 a soil. A compost of lime rubbish, yellow loam, sand, 

 and decayed manure, in equal proportions, suits them 

 well. Several species constitute very charming plants for 

 window gardening, and many others can be grown with 

 great success in the open from May until October. 

 Propagation may be easily effected by pieces, pulled or 

 cut off, and laid in the sun on moist sand, where they 

 root freely in a few weeks. Except where otherwise 

 stated, greenhouse treatment is required for the species 

 here described. 



FIG. 553. BRANCH AND DETACHED LEAF OF MESEMBRYANTHEMUM 

 ACINACIFORME. 



M. aolnaciforme (scimitar-formed), fl. reddish, large, solitary, 

 terminal. August. I. opposite, compressed, triquetrous, acinaci- 

 form, rather curled at the edges, and roughish. Stem rather 

 procumbent, long. 1714. Evergreen trailer. SYN. if. rubro- 

 cinctum. See Fig. 553. (A. B. R. 508 ; B. M. 5539 ; M. A. S. 

 19, Fig. 6.) 



M. adscendens (ascending). /. yellow, pedunculate. August. 

 I. broadly tongue-shaped, very blunt, ascending, green. 1805. 

 Plant stemless, herbaceous. (M. A. S. 8, Fig. 4.) 



ML agninnm (lamb-chop). /. yellow, sessile, solitary, central, 

 expanding in the evening. May. I. semi-terete, serrulated from 

 elevated dots, and hence somewhat toothed, with a large white 

 pustule on the inside at the base. 1824. Plant almost stem- 

 less, canescent, wrinkled from dots, herbaceous. (M. A. S. 

 5, Fig. 8.) 



ML albldum (white-leaved), fl. golden-yellow, large, agreeably 

 scented. June to August. I. greenish-white, subulate, trique- 

 trous ; apex obtuse, mucronate. A. 6in. 1714. Evergreen shrub. 

 (B. M. 1824.) 



M. alblnatnxn (white-marked), fl. yellow, central, solitary, 

 sessile. September. I. acinaciformly triquetrous upwards, with 

 a recurved mucrone, full of scattered, rather elevated, whitish 

 dots. h. 2in. 1823. Herbaceous. 



