AGRICULTURAL SEEDS 1605 



1173 - Agricultural Value of Impermeable Seeds. — Harrington, O. T.,in journal of agricultural 

 Agricultural Research., Vol VI., No. 20, pp. 761-796. Washington D. C, August 14, igi6. seeds 



During the years 1909 to 1916 man}' germination tests of the seeds 

 of clover, lucerne, winter vetch, okra (Hibiscus esctdentns L.) and other 

 plants were made for the purpose of determining the agricultural value 

 of the impermeable seeds. 



Impermeable seeds are those whose coats are impermeable to water 

 at temperature favourable to germination. Such seeds have been de- 

 scribed by numerous investigators under the term " hard seeds " ; the 

 more appropriate term "impermeable seeds" was introduced by Guppy 

 and is iised in the present paper. 



Some plants, cultivated or wild, produce both impermeable and per- 

 meable seeds ; the percentage of impermeable seeds has been determined 

 for some of these species, as follows : 



Percentage of impermeable seeds in some cultivated plants. 



per ceut 



Trifolium pratense 1, 9.61 



T. hyhridum ly 10.16 



T. repens E i7-30 



Melilotus alba Desv 42.39 



Medicago saliva E i3-8i 



Vicia villosa Roth . 20.97 



Vicia saliva E 0.96 



Vigna sinensis (Torner) Savi 3.55 



Mcdtcago hispida denticulata (Willd) Urban 48.08 



Medicago arabica E 71.67 



Medicago saliva falcata (E) Doll 49-72 



Medicago lupulina E 10.45 



Most of the work reported in this paper was done with the seeds of 

 red clover, alsike clover, white clover, white sweet clover, alfalfa, hairy 

 vetch {Vicia villosa Roth) and okra. Some work was also done with 

 crimson clover (Trifolium incarnatum L), black locust {Robinia pseuda- 

 cacia I,), kidney bean {Phaseolus vulgaris L), pea {Pisum sativum ij), cow- 

 pea [Vigna sinensis Sair) and Chamaecrista nicitans L. Muench. 



The following conclusions were reached : It is impossible to distin- 

 guish between impermeable and permeable seeds except by testing their 

 ability to absorb water at a temperature favourable for germination. The 

 production of impermeable seeds is particularly characteristic of the IvCgu- » 

 minosae, but it occurs also in many other plant families. Among the 

 cultivated species which sometimes produce impermeable seeds are okra, 

 holh'hock {Althaea rosea [ly] Cav.), Erodium cicutarium [L] I'Her., Atri- 

 plex spp., asparagus, morning glory {Ipomaea purpurea [L] Lam), canna 

 {Canna indica Iv.), cherry- tomato (Physalis piibescens L.) and nearlj^ all the 

 cultivated species of Leguminosae. 



Impermeable seeds frequently retain their vitality for many years, 

 sometimes for at least as many as 80 years. Fresh impermeable seeds 



