Diseases 



( 304 ) 



Dodecatheon 



Principal Species: 

 bengalensis,15'to 20', sum. 

 hirsute, 6' to 8', red. 



rafflcsiana, 10', red, tliick 

 Ivs. 



DISEASES. 



Plants may be said to be diseased when attacked 

 by animal or vegetable parasites, whereby the 

 organs injured are unable to perform their proper 

 Junctions, bringing about an unhealthy or morbid 

 condition of the plant, and often its death. Gum- 

 ming, or gummosis, is the result of a fungus acting 

 upon the cellulose of the plant. Bacteria may 

 be, and are, responsible for certain diseases. Various 

 fungi gain an entrance into the interior of the 

 tissue of plants, and set up incurable disease. 

 Those fungi that appear on the surface of the leaves 

 and other parts of plants, like the mildew of Roses 

 and Chrysanthemums, may be destroyed by sul- 

 phur, and the plants saved. The American Blight, 

 or Woolly Aphis, sets up a diseased condition of the 

 cellular tissue of Apple trees, but it may be eradi- 

 cated. Eelworms bring about serious diseases. 

 Preventive measures are necessary. Various 

 diseases are dealt with under their respective 

 names, or under the crops they attack. 



DISPERIS. 



A small genus of terrestrial Orchids (ord. 

 Orchidaceaj) from South Africa. They may be 

 grown in a cool house in a mixture of fibrous loam 

 and peat, to which has been added some small 

 crocks and charcoal. They may be increased by 

 division of the tubers when repotted in spring 



Principal Species : 



capensis, 9", Jy., sc, secuuda 9", Je.. pur 



cucullata, 9", Je. , pur 



DISPORUM. 



A little grown genus (ord. Liliacea;) of plants, 

 resembling the Uvularias, and only hardy here in 

 the south of England and Ireland. They grow 

 best in partial shade in a border of moist, peaty soil. 



Principal Species and Varieties : 

 lanugiiiosum, 1', My., variegatum, grn., wh. 



grh., yel., grn. (syn. Menziesii, 1' to 3', grn. 



TTvularia lanuginosa) . pullum, 11', Sep., br. 

 (xi/tix. fulvum and 

 Uvularia chinensis). 



Hookerii, 2', greenish, 

 lescheuaultianum, I'to2', 

 spr., wh., berries bit. 



parviflorum. 



DISSOTIS. 



Stove shrubs (ord. Melastomacea?) with promi- 

 nently nerved leaves covered with fine hairs, and 

 numerous red or purple flowers 1" across. They 

 are readily increased by cuttings in spring, and 

 succeed in a mixture of two parts sandy peat 

 and one part fibrous loam. 



Principal Species : 



incana, 2', sum. , pur. johustoniana, I. 1 ,', sum., 



irviugiaua, 2' to 3', sum., pur. 



red pur. plumosa, 2' , sum. , red pur. 



DISTEGANTHUS. 



A small genus (ord. Bromeliacea?) found, like 

 many other Uromeliads, growing in clefts on trunks 

 of trees in moist South American forests. They 

 require well-drained pots and a mixture of peat, 

 charcoal, and sand, with plenty of fresh water 

 throughout the summer. 



Ditelma (see Fitzroya). 



Dixemma aurantia (see Pas.nflora llanltsii). 



JOlsocactus (see I'hyllocactits). 



Principal Species : 



basilateralis, yel. 



scarlatimis (sec Distia- 

 canthus scarlatinus). 



DISTIACANTHUS. 



Stove herbaceous plants (<Y/. Bromeliacea?), 

 answering to the same cultural treatment as the 

 Billbergias. The leaves, which are in rosettes, 

 have spiny margins. 



Only Species : 



morreiiiamis, yel. (si/us. 

 Cryptanthus morren- 

 iauus and Distegauthus 

 Moensii). 



scarlatinus, pur. reel, 

 margined wh. (xyns. 

 Bromelia scarlatina 

 anil 1 )isteganthu-i scar- 

 latinus). 



DISTYLIUM. 



Greenhouse evergreen shrubs or small trees 

 (ord. Hamamelidere), propagated by cuttings, and 

 thriving in a mixture of two- 

 thirds of loam, one - third of 

 leaf soil, and sand. They are 

 not in general cultivation, race- 

 mosnm and its variegated form 

 being the only members of the 

 genus met with. 



DIURIS. 



Stove terrestrial Orchids (ord. 

 Orchidacea?). Propagation is 

 by division, and for soil two- 

 thirds of leaf soil and one-third 

 of sand are suitable ; or the 

 plants may be grown in sandy 

 peat. The pots should be half 

 filled with crocks. 



Principal Species : 



alba, 1', Aug., wli., ro., grn., br. 



pur. . 

 maculata, 1', Mch., yel., spotted 



br. pur. (synx. curvifolia and 



pardina). 

 punctata, 1' to 2', bl., pur. (M/M.V. 



lilaciua and elongata). 



DOCK. 



A troublesome weed, espe- 

 cially in rough, heavy soil. It 

 is difficult to eradicate, as 

 each piece of root left in the 

 ground will make a new plant. 

 Thorough cultivation is the 

 only cure. Dock leaves form 

 a cooling and soothing application for Nettle 

 stings. For species, see RU.MKX. 



DODECATHEON. (AMERICAN COWS- 

 LIP, SHOOTING STAR.) 



Charming little plants (ord. Primulacese), hardy 

 in our gardens, and admirably adapted for shady, 

 moist nooks in the rock garden. They have pretty 

 heads of flowers with reflexed petals. Propagation 

 is by division in spring, or after flowering, and by 

 seeds sown when ripe, or in spring, in pots or pans 



Distrepta (see Tecopkilifa). 

 Dittany (see Dictammis). 

 Dittany of Crete (see O,iyanuiii'). 

 Dittmaria (see Erimna). 

 Divi-divi (see Ctesatpinia). 

 Dodder (see Ouscuta). 



DoollIA ASl'IiUA 

 CKISTATA (see p. 306). 



