AN ENCYCLOPAEDIA OF HORTICULTURE. 



365 



Mignonette continued. 



floriferous and the flowera sweetly scented. For pot 

 culture, it is most desirable that they should be of 

 a vigorous yet compact habit, and of a uniform strength 

 throughout. If several varieties are grown near each 

 other, the flowers will be almost certain to become 

 cross-fertilised by insect agency, and the product will 

 always degenerate rather than improve. Distinct and 

 superior forms often owe their origin to a rigid selection 

 being annually made of the very best plants for seed- 

 bearing, and the weeding out before the flowering period 

 of all showing the least inferiority. Nurserymen, doubt- 

 less, do all in their power to retail seeds true to 

 character; but whenever pot culture of Mignonette is 

 practised, and a good type is once obtained, the cultivator 

 should rigidly weed out, from the first, plants of irregular 

 growth, and save seed himself from the others, sufficient, 

 at least, for growing in pots the following year. The 

 standard of quality would be much improved, even in one 

 season, by such a selection, and far less " weeding " would 

 be required afterwards. The seed must be collected so 

 soon as it begins turning brown; and laid out on paper, 

 in a cool, airy room or shed, to dry, when it may be 

 rubbed out, cleaned, and stored in paper bags. If 

 allowed to get quite ripe before being collected, the 

 best seeds will be lost, in consequence of the seed-vessels 



FIG. 569. RIPE SEED-VESSEL OF MIGNONETTE. 



(see Fig. 569) being always open at the apex, and 

 naturally situated at an angle well suited for readily dis- 

 charging their contents. 



Varieties. Of these, there are several in cultivation, 

 some having what are termed red, and others white, 

 flowers. The old common type of Mignonette is well 

 known, and is one of the most sweetly scented. The fol- 

 lowing is a selection from the best varieties. There is a 

 double-flowered form in cultivation, which must be pro- 

 pagated from cuttings. 



Crimson King. Flowers bright red, sweetly scented; habit 



dwarf, vigorous, pyramidal. A new and distinct variety, most 



desirable for pot culture. 

 Dwarf Erect. Flowers erect, produced in stout, densely-set 



racemes ; habit dwarf and neat. 

 Caraway's White. Flowers white ; racemes large and long. 



One of the best, either for outside culture or for pots. 

 Giant Pyramidal. Flowers reddish, sweetly-scented ; racemes 



very large. The plant is of a stout pyramidal habit, and succeeds 

 tside. 



well out 



ery distinct; habit 



Golden Queen. Flowers golden-yellow, 

 dwarf and compact. An exceedingly fine Mignonette, of dense 

 growth, very floriferous. 



Machet. A new dwarf variety, of French origin, having very 

 fragrant flowers of a bright red colour. The habit is robust, and 

 the racemes broad. Highly recommended for pot culture. 



Miles' Hybrid Spiral. Flowers white, very fragrant, produced 

 in dense racemes, sometimes exceeding 1ft. in length. The 

 habit is dwarf and branching, and the variety, when obtained 

 true, is one of the best in cultivation, especially for pots. 



Parsons' White. Flowers nearly white, strongly scented ; 

 racemes long and well-formed. An excellent variety. 



Queen Victoria. Flowers deep red, very fragrant, profuse; 

 habit dwarf, branching. Fine and distinct. 



MIKANIA (named after Joseph Mikan, 1743-1814, 

 one Professor of Botany at Prague). STN. Willugbceya. 

 ORD. Compositce. A large genus (about sixty species have 

 been described) of stove, evergreen climbers, natives, for 

 the most part, of tropical America, allied to Eupatorium, 

 but distinguished in the flower-heads containing generally 

 only four florets, and the involucre having as many nearly 

 equal bracts. For culture, see stove species of Eupa- 

 torium. 



Mikania continued. 



M. apiifolia (Apium-leaved). floods yellowish, small, in lax 

 corymbs. Summer. I. dark green, quinate, membranaceous, 

 glabrous, evergreen; segments entire or pinnatifid. Brazil. 

 A pretty climber. (I. H. 1885, 549.) 



M. Gnaco (Guaco). fl.-heads pale blue. L stalked, ovate, sub- 

 acuminate, remotely toothed. South America, 1823. Climbing 

 perennial. 



M. scandens (climbing).* fl.-heads yellowish-white, cylindrical, 

 corymbose. Summer. I opposite, cordate, glabrous, shining. 

 Brazil, 1823. This slender climbing perennial is very suitable for 

 growing over trellises, and similar pkces, in the open air, during 

 the summer months. 



MILDEW. A name sometimes applied to several 

 kinds of microscopic fungi that live as parasites on 

 various flowering plants, cultivated and uncultivated ; it 

 is, of course, on the former that their occurrence is of 

 interest to the horticulturist. The name is believed to be 

 connected with the German Mehl-thau, or Meal-dew, 

 because of the appearance some Mildews give the affected 

 parts of being sprinkled with flour or meal. Besides 

 living on plants, the Mildews are also found on cloth, 

 on paper, on leather, and even on glass ; but the forms 

 growing on these need not be further adverted to here. 

 Nor is it necessary to dwell upon the Mildew of Wheat, 

 Barley, and other grasses, which, if forming dark brown 

 spots, is caused by a species of Puccinia (usually 

 P. graminis); or, if the spots are orange, by the uredo- 

 spores of the same fungi. The Mildews of most conse- 

 quence in gardens are white, and form a coat all over the 

 leaves and young shoots of the plants attacked by them. 

 On microscopic inspection, this is found to consist of 

 slender, creeping threads, which branch freely, and give off 

 branches that rise erect into the air as slender filaments, 

 made up of a single row of cells, of which the terminal 

 ones are larger, oval, and break away from the tip back- 

 wards, to form spores, which serve for the reproduction of 

 the fungi. Very many plants are liable to be attacked by 

 this white coating, and there is reason to believe that 

 there are many kinds of it, though all much alike. The 

 various kinds are included, as species, under the genus 

 Oidium ; but they are known to be merely a stage in 

 development of more highly developed fungi, belonging 

 to Erisyphece. If some kinds of Oidium, e.g., those on 

 Peas, on Hops, or on Eoses, are watched, it will be found 

 that, after a time, the surface becomes studded with 

 small, yellowish objects, which soon grow darker in 

 colour, and at length become quite black, and resemble 

 grains of gunpowder, scattered abundantly over tho 

 Oidium. With the microscope these are seen to be 

 fruits of the fungus. Each is a slightly-flattened sphere, 

 with a thin, black wall, formed of cells (peritheciumj 

 surrounding several small transparent bladders (asci), 

 each of which incloses two, four, or eight (rarely six) 

 spores. These are believed to be the result of sexual 

 reproduction. They are very small, and are easily car- 

 ried about by the wind, or by other means. If they fall 

 on a suitable host-plant, they push out a fine thread, 

 which reproduces the Oidium stage once more. The 

 threads of the Oidium lie on the outer surface of the 

 plants (not penetrating among the cells, like the Potato 

 Disease fungus, and many others), where they form a web, 

 nourished by means of small branches (haustoria, or 

 suckers), that penetrate into the outer cells (epiderm) 

 of the plant, and absorb food from the cell contents. 

 Some kinds of Oidium have not yet been traced to the 

 sexually mature form, e.g., Oidium Tuckeri, which is often 

 very hurtful to Vines ; 0. Bnlsamii, on Turnip leaves, &c. 

 Besides these two, the following White Mildews, of which 

 the fully- developed state is known, are, at times, destruc- 

 tive to garden plants : Sphoerotheca pannosa, in dense, 

 grey patches, on Peach and Rose twigs and leaves; 

 S. Castagnei, very injurious to Hops, as well as to many 

 weeds ; Podosphcera Oxyacanthce on Hawthorn twigs and 

 leaves ; Erisyphe Martii on Peas, and other leguminous 

 plants, and on many weeds ; E. communis and E. Cicho- 



