432 



THE DICTIONARY OF GARDENING, 



Nelnmbinm continued. 



placed in shallow water. It thrives in warm sheltered tanks 

 in the open during summer. This plant has been regarded 

 from the most remote periods as the emblem of fertility. (B. M. 

 903, 3916, 3917.) There are several varieties of this species. 



NEMACONIA. A synonym of Fonera (which see). 



NEMASTYLIS (from nemo., a thread, and stylos, 

 a column; referring to the slender style). SYNS. 

 Chlamydostylis, Eustylis, Nemostylis. ORD. Iridece. A 

 genus comprising about half-a-dozen species of half- 

 hardy bulbs, natives of Mexico and North and tropical 

 America. Flowers in few or somewhat numerous- 

 flowered spathes, pedicellate ; perianth segments ovate ; 

 spathe oblong or narrow. Leaves narrow, long, some- 

 times sub-terete, rarely narrow-ensiform ; floral leaves 

 one or two. Bulb tunicated. The species thrive in well- 

 drained sandy loam: for pot culture they do best in a 

 cold frame near the glass, or in a light, cool house. After 

 the leaves have died off, the pots must be kept dry 

 and stored in a cool place until the following spring. 

 Increased by bulb offsets, or by seeds. 



N. acnta (acute).* fl. blue, yellow, black, solitary, terminal, very 



fugacious, falling to pieces within a few hours of their opening. 



h. 6in. South-western United States, 1875. SYN. N. geminiflora. 



(B. M. 6666.) 

 N. coelestlna (celestial blue), fl. bright blue, mostly solitary, 



terminal ; perianth six-parted, the divisions oblong-obovate. 



May and June. 1., radical ones few, elongated, sheathing ; stem 



ones diminishing upwards, the uppermost bract-like. Stem lift. 



to 2ft high. South United States, 1882. (R. G. 1081, Fig. 1.) 

 N. gemlnlflora (twin-flowered). A synonym of N. acuta. 



NEMATANTHUS (from nema, nematos, a thread, 

 and anthos, a flower ; the flowers of one species hang down 

 from long, thread-like footstalks). ORD. Gesneraceas. A 

 small genus (three or four species) of very ornamental, 

 stove, evergreen, climbing, fleshy, Brazilian shrubs. Flowers 

 large, solitary or twin, axillary ; corolla with an obconical 

 tube gradually merging into a funnel or bell-shaped ex- 

 pansion. Leaves opposite, thick, entire, glabrous. The 

 species thrive in a compost of sandy peat and turfy loam, 

 with charcoal and dried cowdung. Propagation may be 

 freely effected by cuttings inserted in sandy soil, and 

 kept rather dry. 



N. chloronema (green-threaded), fl. scarlet, 2in. long, beset with 

 white hairs outside. July. I. oblong-lanceolate, acuminated at 

 both ends. 1841. (B. M. 4080.) 



N. corticicola (epiphytal), fl. scarlet, beset with scattered 

 minute hairs : peduncles 6in. to 12in. long, clothed with violaceous 

 and white hairs. I. broad-lanceolate, acuminated at both ends. 

 1848. (B. M. 4460 ; F. d. S. 498, under name of N. ionema.) 



N. ionema (violet-threaded). A synonym of N. corticicola. 



N. longlpes (long-stalked). /. bright red, about 2in. long, with 

 the segments of the tube suddenly reflexed ; stalks thread-like, 

 Sin. long. December. I. thick, fleshy, oblong, deep green. Stems 

 erect, IJft. high. 1841. (B. M. 4018.) 



NEMATOCERAS. A synonym of Corysanthes. 



NEMATOID WORMS (Anguillulidae). The im- 

 portance of this group of microscopic animals, as giving 

 rise to disease in both wild and cultivated plants, is 

 becoming ever more fully recognised with the extension 

 of careful researches into the nature of diseases that 

 were formerly ill - understood. They differ much from 

 the earthworms, and other true worms, and exhibit 

 a much lower type of structure. They are minute, 

 white or translucent, and usually so small as to re- 

 semble short, slender, pieces of hair, even when visible 

 at all without a magnifying glass. All those kinds that 

 cause disease in plants are very minute, and live in 

 the interior of the parts they attack, so that these parts 

 must be cut into, or opened, before worms can be dis- 

 covered. When seen through a microscope, they appear 

 slender, tapering both ways, but the front end, in which 

 is the month, is rather blunt, the hinder end, or tail, 

 is usually long, and tapers gradually, or it may bear an 

 extension of the skin along one or both sides. There 

 is no head; nor are there limbs or organs of sense of 



Nematoid Worms continued. 



any kind visible. The month opens in front ; on the 

 gullet and intestines there are usually two swollen mus- 

 cular bodies, which serve for helping to prepare tht 

 food in its passage downwards. The intestine opens 

 below in the anus, some distance from the end of the 

 body, the tail, of varying length, lying behind it. The 

 characters of the genera and species are recognisable 

 usually in the mature animals alone. The situation of 

 the sexual openings, and, in the males, two horny out- 

 growths, connected with reproduction, assist in supply- 

 ing distinctive characters, as do also peculiarities in 

 the internal organs, which can be made out, with no 

 great difficulty under the microscope, in the living 

 animals. The Anguillulidae are very numerous in species, 

 and they show considerable diversity in habits and 

 modes of life. A few live as parasites in the intes- 

 tines of animals, e.g., Oxyuris vermicularis in man. 

 Many, probably most, live free in damp earth, or in 

 mud in which there is abundant decaying organic 

 matter, or in decaying plant-remains under water. A 

 certain number live in plants; some in the roots, pro- 

 ducing galls or swellings ; others in the green vegetative 

 organs (e.g., in leaves of Plantago, of some grasses, such 

 as Agrostis alba), or in the ovary (e.g., in Wheat). Only 

 the plant parasites are here dealt with. They chiefly 

 belong to a genus called Tylenchus, though much atten- 

 tion has been drawn to the ravages of another Nema- 

 tode, known as Heterodera Schachtii, because of the 

 injury done by it, in Germany, to the roots of the 

 Sugar Beet, as well as to other plants both wild and 

 cultivated. The species of AnguillulidcB seem to be 

 very widely diffused over the world ; though the diffi- 

 culties of identifying the species are so great as to 

 render unreliable the conclusions arrived at by anyone 

 save an expert. The plant parasites usually give rise 

 to a much-increased growth of cellular tissue, thus pro- 

 ducing galls of a characteristic aspect. On microscopic 

 examination of sections of the galls, the cells in them 

 are generally found to be much larger than in healthy 

 tissues, and less regular in arrangement and form; and 

 they leave large inter-cellular spaces, or else one large, 

 irregular central space, in which are found numerous 

 young animals, together with oval or cylindrical eggs, 

 the walls of which are so thin as to allow the young 

 animal coiled up in each to be easily seen. Less fre- 

 quently, along with these may be seen one or two mature 

 individuals. The galls have usually a peculiar colour, due 

 to sap in the cells near the surface. As a rule, there 

 is no trace of an opening to be seen in the mature 

 galls. The young animals seem to be dispersed chiefly 

 by the galls decaying and setting free the eggs or 

 young in the soil, to be blown about with the dust in 

 dry weather. Several of the species notably that which 

 causes " bunt " in wheat (Tylenchus Tritici) have a 

 curious faculty of reviving in moisture, after having been 

 dried up for months, or even years. They also seem 

 capable of enduring extremes of cold and heat, up to 

 125deg. Fahr., without being destroyed ; and they are 

 not susceptible to vegetable poisons, though they perish 

 in solutions of acids and of most metallic compounds. 

 In pure water, they survive for a long time. 



Cereals are very liable to be attacked, Tylenchus 

 Tritici galling the ovaries, while T. devastatrix, Kiihn 

 (T. dipsaci, J. Kiihn), attacks the stalk, and the inflo- 

 rescences of the Eye, of various other grasses, and of 

 many other plants, e.g., the Teasel (Dipsacus Fullonum), 

 Clovers, Buckwheat, &c., causing them to remain stunted, 

 with short internodes, and to become yellow. The former 

 species is not troublesome to gardeners ; the second one 

 is injurious to many cultivated, as well as to unculti- 

 vated, plants. Both species of Tylenchus live entirely 

 hidden from sight, as already described. The males of 

 the genus Tylenchus have usually a thin skin or free 



