AN ENCYCLOPEDIA OF HORTICULTURE. 



433 



Nematoid Worms continued. 



membrane attached along one side of the hinder part of 

 the body and the tail. Many other plants suffer through 

 attacks of animals of the same genus ; but the hurtful 

 species are not fully known, and considerable doubt exists 

 as to their true number as well as to their relationship to 

 one another. During the past few years, their presence 

 in a good many garden plants has been recorded in the 

 " Gardeners' Chronicle," and other horticultural journals. 

 The diseases produced by them often seriously damage, 

 if they do not even kill, the plants. Not less dangerous 

 than the above are the Nematodes that gall the roots 

 of plants. The swellings usually are to be seen on the 

 root tips, though often they occur higher up the root. 

 They vary greatly in size, from little larger than a pin's 

 head, on fine roots, to the size of a hazel-nut, or even 

 larger. They are usually nearly round, or oval, though 

 irregular forms are also common. The swelling is due to 

 increase in the cellular tissue alone, the fibro-vascular 

 tissue being hardly altered in any way. They are known 

 to occur on a very large number of plants, both native 

 and exotic, wild and cultivated, from grasses to Clover, 

 and even on Coffee-trees, in South America. Among the 

 most valuable plants injured by them must be specially 

 mentioned the Sugar Beet, in its various forms, and 

 also occasionally the Grape Vine. 



In the galled roots of many plants a Nematode is met 

 with, characterised by the fertile female becoming swollen, 

 so as to resemble a lemon in form, with traces of the 

 head and tail at the two ends. The female's body be- 

 comes united to the surrounding tissues, so as ultimately 

 to look like a large cell merely, in which lie eggs, or 

 young larvse newly emerged from the eggs. This Ne- 

 matode has received the name of Heterodera Schachtii. 

 Attempts have been made to show that almost all root 

 galls of Nematodes are the work of this species; but in 

 Scotland the writer has never met with Heterodera in root- 

 galls, but only with true species of Tylenchus. The 

 animals, in autumn, pass from the food-plants, when 

 these die and decay, into the surrounding soil, ready to 

 make their way the following spring to the new crop of 

 food-plants, should there be any such within their reach. 

 Hence, the best mode of prevention consists in changing 

 the crops on any piece of ground, so as to prevent suit- 

 able food for the Nematodes being afforded during the 

 ensuing season. On infested soil, therefore, plants liable 

 to attack should be followed by others unsuitable as 

 food for the Worms. It is well, also, to use only clean 

 seed, from a crop in which the disease has not appeared ; 

 and farmyard manure is somewhat dangerous, as liable 

 to spread the Worms from diseased to healthy plants, 

 either in the garden or the field. 



If any plants show signs of being severely attacked, 

 they should be at once burnt, to prevent extension of 

 the disease from them to others that are healthy. 



NEMATOPHYLLUM. Included under Temple- 

 tonia (which see). 



NEMATOSTIGMA, of Dietrich. A synonym of 

 Libertia (which see). 



NEMATUS. A very large genus of Tenthredinidce, 

 or Sawflies, of much importance because of the harm 

 done by the larvae to various trees and shrubs, but 

 especially to Willows, Gooseberries, and Currants. They 

 are the type of a sub-family, Nematina, that has the 

 larva provided with fourteen sucker feet. In this sub- 

 family it is distinguished from the other genera by the 

 form and arrangements of the nerves of the front wings, 

 and of the cellules formed by them. The insects are 

 never large, and they bear so great a likeness to one 

 another that it is most difficult to distinguish the 

 species, since they are mostly smooth and shining, are 

 seldom, if ever, punctured, and do not vary in pubes- 

 cence. By their colour, the srecies may be divided 



Vol. IL 



Nematus continued. 



into groups : (1) Abdomen wholly black ; (2) abdomen 

 banded with red; (3) body black and yellow; (4) body 

 wholly yellow, or slightly marked with black ; (5) body 

 green. These groups, however, grade into one another. 

 Mr. Cameron, in his work on British Sawflies, says 

 that there may be 400 species of this genus in Europe, 

 and he describes 107 from Britain alone. The larvae 

 vary much in habits. Some are gregarious, while others 

 are solitary ; most feed exposed, but some roll up the 

 edge of the leaves, to form a tube, in which they live ; 

 and others form pea or bean-shaped galls on the leaves 

 of Willows. Indeed, few kinds of these latter plants are 

 entirely free from their galls ; while on some bushes 

 almost every leaf is loaded with them. The larvae, when 

 full fed, generally burrow an inch or two into the soil, 

 and there form cocoons. The papas are usually green, 

 often with a mixture of orange. It is impossible here 

 to enumerate all the trees and bushes that are attacked 

 by the larra; but a few of the more important are 

 described. Gooseberries are ravaged by N. Ribesii, 

 N. appendiculatus, and N. consobrinus ; N. abbreviates 

 feeds on Apples and Pears ; several kinds feed on Alder, 

 others on Birch ; very many are to be found on Willows 

 of all species. Of the Willow Sawflies, the following 

 are gall-makers: N. vesicator, in bean-shaped galls in 

 the leaves; N. ischnocerus, in rather long galls, in 

 pairs along the midribs of the leaves ; N. baccarum, 

 N. salicis-cinerece, and N. bellus, in pea-shaped galls on 

 the lower surface of the leaves of various Willows; 

 N. herbacece, in similar galls on Salix herbacea ; N. galli- 

 cola, in the bean-shaped galls so plentiful in leaves of 

 Salix alba and other large Willows ; and N. Bridgmanni, 

 in similar galls from Sallows ; N. Vacciniellus forma 

 galls on Vaccinium Vitis-idcea. For methods of checking 

 the ravages of such larvas as feed exposed, see Goose- 

 berry and Currant Sawfly. 



NEMESIA (an old Greek name employed by Dios- 

 corides to denote an allied plant). OBD. Scrophularinece. 

 A genus comprising about a score species of very pretty, 

 South African, greenhouse, slender, annual or perennial, 

 sometimes suffruticose, herbs. Flowers racemose at the 

 tips of the branches, or rarely solitary in the axils; 

 pedicels ebracteolate ; corolla yellow, white, violet, or 

 various-coloured. Leaves opposite. The few species in 

 cultivation are treated as hardy annuals. Propagated by 

 seeds, sown in early spring, in any ordinary soil. The 

 seedlings should be thinned out when large enough to 

 handle. 

 N. cynanchlfolia (Cynanchum-leaved).* /. rich lilac-blue, in 



terminal clusters. Summer. I. ovate-lanceolate, remotely toothed. 



Stems square, h, lift, to 2ft. 1879. A pretty species. (G. C. 



n. s., xii. 136.) 

 N. floribunda (bundle-flowered).* /. white and yellow, fragrant, 



racemose. Summer. I. at length petiolate ; upper ones sessile. 



h. 1ft. A very charming plant. (B. R. 1838, 39.) 

 N. versicolor (various-coloured), fl. blue, lilac, or yellow and 



white ; racemes few-flowered. Summer. I. at length petiolate, 



ovate ; upper ones few, remote, sessile, oblong-lanceolate or linear, 



entire or dentate, h. 6in. to 12in. 



NEMIA. A synonym of Manulea (which see). 



NEMOPANTHES (from nema, a thread, and anthos, 

 a flower ; in allusion to the filiform peduncle). Mountain 

 Holly. STN. Nuttallia, of De Candolle. ORD. nicinece. 

 A monotypic genus, the species being a very glabrous, 

 much-branched, hardy shrub, with ornamental berries. 

 It thrives best, in cold damp soils, in somewhat shaded 

 spots, and is most readily propagated by means of 

 seeds. 

 N. canadense (Canadian), fl. small, polygamo-dioecious, on long 



and slender axillary peduncles, solitary or sparingly clustered; 



petals four or five, oblon-linear, spreading, distinct. May. fr. a 



light red drupe, with four or five bony nutlets. I. alternate. 



oblong, deciduous, entire or slightly toothed, h. 3ft. North 



America, 1802. SYNS. Ilex canadensis and Prinos integrijoliw. 



(A. F. B. ii. 503.) 



3 K 



