496 DISEASES 



to be one of this class, and is as interesting to the vege- 

 table pathologist as it is destructive to the orchardist. 

 The latest view of this particular form of disorder is 

 that of the unorganized ferment, which by causing cer- 

 tain chemical changes in the substances of the cells brings 

 about the peculiar and well marked malady of the "yel- 

 lows." If we start with the premise that there is a cer- 

 tain small amount of chemical ferment in all plants, it 

 is only necessary to have this increased to get the re- 

 sults in question; and how to prevent this augmentation 

 is the practical point at issue. This ferment in active 

 form might be communicated from one plant to another 

 by budding or grafting, and, instead of introducing liv- 

 ing germs, it is a transmission of a germless ferment 

 like diastase, that is found in seeds, and does its ap- 

 pointed work as a solvent, in the period of germination. 

 There are other disorders that are called " ffidema," or 

 a dropsical form of disease. The tomato is subject to 

 this, and pelargoniums likewise. Tumors are formed, or 

 the leaves bear translucent dots along the veins. This 

 trouble is most apt to appear with greenhouse plants in 

 early spring, and may be favored by lack of sun- 

 shine, especially if tlie warm soil is wet and root action 

 is excessive. The remedy lies in furnishing, so far as 



DISPORUM 



possible, the conditions opposite to those above named. 



In general, it may be said that diseases which are 

 due to germs or to malnutrition show the disorder 

 more or less generally spread over the plant, rather than 

 confined to local areas. For example, if the foliage 

 shows a general wilting, it is evident that the trouble 

 lies farther back than the leaves themselves. If one 

 leaf begins to die all around the edge (as in Fig. 726), it 

 is in*ication that the trouble is a cutting off of food 

 supply in the entire leaf; the trouble may be near the 

 base of the leaf, or farther back. After a time, the leaf 

 becomes dry and brittle, and the winds break it. In Fig. 

 727 it is evident that the trouble is in the whole branch. 

 Byron D. Halsted. 



DISHCLOTH GOUBD. See Luffa. , 



DISPORUM (Greek, double pored). LUiicem. Per- 

 ennial herbs with the appearance of our much-loved 

 eastern Bellwort or Uvularia, but distinguished by an 

 indehiscent ben-y, while Uvularia has a capsule that 

 splits down the back of each cell. In 1879, Bentham ;ind 

 Hooker proposed to include Prosartes in this giniis. 

 The American species of Prosartes are said by S. A\:itMin 

 to differ from the Asian ones in having tlifirorulis Imng 

 from the top of the cell instead of as.-.ii.ijn- ficm iho 

 base, but in one American species, /'. ti;i'l,<i, .i ,■!.■: . ih. y 

 are fixed on the sides, as they are als<p in "ii. HiiiKila\an 

 species. The habit of all is said to l.i- aliki. Latest 

 monograph of both genera by Baker in Journ. Linn. Soc. 

 14 586, 588 (1875) , of the American species of Prosartes 

 by S Watson, m Proc Am. Acad. 14:270 (1879). 



These plants have been little tried in the eastern 

 states and are probil h not hardy without some winter 

 covermg 



A Lis 



; S-cUft. 



B Peiianth iciy 1 1 t ! nml uinquuUii rotmded at 

 Uh base. 



M§nzi8Bii, Nicholson (P. MinziesU, Don). More or 

 less woolly pubescent stem 2-3 ft. long, forking, arch- 

 ing above Ivs ovate to ovate-lanceolate, narrowly acu- 

 minate or the lowest acute, sessile, 2-3 in. long, often 

 resm dotted fls 1-3 greenish, from the topmost axils, 

 nodding 7-9 lines long pedicels puberulous; perianth 

 segments nearly erect, acute, 6-11 lines long; stamens 

 a third shorter , anthers included, l}^-2 times shorter 

 than the filaments berry 3-6 seeded: cells 1-2-seeded: 

 fr oblong obovate, narrowed to a short beak. Calif, 

 to B C 

 BB Pcttanth narroH and m")-' ^r. ,ij, ...h., i^. ,] ,,t the ha.^e. 



lanugindsum, Nicholson. W ■ "t: Ivs. ob- 



long lanceolate, narrowlv acini ■ ' ill --'•ginciits 



greenish, linear lanceolate. a.uii;ii):iii . ^pi. a. ling, 6 or 7 

 lines long, stamens a third sh(»rter; style and narrow 

 ovary glabrous capsule oblong-ovate, obtusish or with 

 a very short, stout beak, glabrous ; cells 1-2-seeded. 

 W N Y to Ga and Tenn. B.M. 1490.-Int. by H. P. 



plsev 



trachyc&rpuin, Hook & Jack. {P. trachycdrpa ,Wa,ts.) . 

 M re or less pubescent stem 1-13^ ft. high, forking, 

 « ith foliage on the upper half: Ivs. ovate to olilong-lan- 



I il I 1 1 uitli sc gments whitish, sliulii l\ -i.iiinnn-. 



I t ri \ l\ I I tnteolatethan in /'. '/ .i-'. 



t I 111 1 1 I ut as long as tin i rv 



I i\ II lis 2-6 seeded: fr. bn. mill ., I..., ,in, .ili- 



II 1 ithi 1 (liiplj lobed, papillose. Saskati'luwuii to 

 Idaho, I tih and Colo 



AA iis mosHy cordate-clasping. 



Oreg4num iP Oiegdna, S. Wats.). More or less 



II 1 ii It h s ovate to oblong-lanceolate, long- 



I III nth segments spreading, acute, nar- 



I I I 1 \ listmctly net-veined, 5-7 lines long, 



i 1 1 li rter than the stamens : fr. ovate. 



It pubescent; cells 1-2-seeded. Oreg. 



1 1 Idaho to B C 

 I he following kinds 



with short, 

 II. s oblong: perianth 

 it.ise; cells nsu.illy 2- 

 more robust form of 



