APPENDIX 567 



NOTE 43 (page 102) 

 On the Mucosity of Small Seeds and Seed-like Fruits when 



WET 



I paid considerable attention to this subject from the standpoint of 

 dispersal some years ago, and published most of the -esults in Science Gossip 

 for Sept., 1894. This peculiar quality of seeds had been noticed by Dr. 

 Kerner in his Pflanzenleben (vol. i., 1887-91), and was regarded as illus- 

 trating a mode of dispersal of seeds by adherence. As a rule, such seeds 

 when placed in water become coated with mucus in a few minutes, or 

 within an hour, and when allowed to dry on feathers they adhere as firmly 

 as if gummed. I found that this quality is not affected by prolonged 

 drying, as in the cases of Nepeta glechoma and Salvia verbenaca, where it 

 was exhibited to the same degree after the seed-like fruits had been kept 

 from one to three years. I especially tested about no British plants that 

 were likely to display this quality, and found that about a dozen exhibited 

 it in a marked degree, and if to these we add those plants wiuh seeds that 

 display it to a limited extent so that they merely become adhesive when 

 wetted, the total would be nearly twenty. It will be noticed from the list 

 subjoined that the plants showing marked mucosity belong to twenty genera 

 and to ten families, the Labiatre and Crucifer^e predominating. Although 

 in some genera, like Plantago, there is reason to suppose that the seeds of 

 all the species would behave in this fashion, it would be wrong to infer that 

 this is usually the case, six genera being indicated below to which such a 

 rule would not apply, and doubtless the number could be extended. 

 These plants in England mostly occur at the roadside, on waste ground, 

 and in dry meadows. It may be added that although in most cases the 

 seeds appear in water to emit mucus, "exuded mucilage" being the 

 expression used in the English edition of Kerner's work, in some instances, 

 as with Helianthemum vulgare, there appears to be a dissolving process 

 affecting the outer seed-covering. 



I. Plants with Seeds or Seed-like Fruits that emit Mucus to a Marked 



Degree when placed in Water. 



Arabis thaliana, G. 



Camelina sativa, K. 



Teesdalia, K. \ Cruciferte. 



Capsella bursa-pastoris, G. 



Lepidium sativum, D. 



Helianthemum vulgare, G. Cistaceae. 



* Viola tricolor (Field Pansy), G Violacea;. 



Linum usitatissimum, D. 1 ^ . 



T . „ \ Lmaceas. 



Linum, K. ) 



