420 THE BIOLOGY OF FLOWERING PLANTS 



germinated, nor did those of the Revolution, nor even those 

 of the I St Empire. Ewart also found that the longest-lived 

 seeds were Leguminosae. In general, the long-lived seeds 

 are hard coated with a resistant testa which prevents water 

 absorption while intact and is impervious to gases. 



Seeds in Soil and Water. — These are cases of seeds 

 stored in ordinary dry air, but many seeds can remain 

 dormant for long periods in moist soil or in mud. It is well 

 known that on the mud of drained ponds, or on the soil of 

 old pastures and woodlands freshly turned up, a vegetation 

 rapidly appears with many species not occurring under the 

 previous conditions. Some of these may arise from seeds 

 recently transported, but others must spring from seeds 

 which have long lain dormant in the soil. Peter (1893) found 

 that forest soil to the depth of a foot contained seeds capable 

 of germination when the soil was turned up and kept moist. 

 In the soil of primitive forest, seeds of woodland species 

 only, such as the strawberry and raspberry, were found ; 

 in the soil of woodland planted on cultivated land 20 to 

 40 years previously, seeds of such plants as shepherd's 

 purse, charlock, and plantain sprouted ; it is difficult 

 to avoid the conclusion that these had lain dormant since 

 planting, or at least since the shade of the trees had sufficed 

 to expel the previous flora. Brenchley (19 18) found that 

 when grassland which had replaced arable was ploughed up, 

 seeds of arable weeds (16 species in one case after 10 years 

 in grass) sprouted which had lain dormant in the soil for 

 periods up to 58 years. Such weeds never appeared on 

 grassland turned up for the first time. Darlington (1922) 

 reports on a controlled experiment started by Dr. W. Beal. 

 Seeds in moist sand placed in open bottles were buried 

 3 feet deep. After 40 years 10 out of 22 species were still 

 viable. These included Rumex crispus, Plantago major, and 

 Amarantus retroflexus. It is of interest that under these 

 conditions Trifolium did not germinate after 5 years, nor 

 Malva after 20 years. G. H. Shull (1914) showed that the 

 seeds of many land plants might remain dormant in glass 

 jars submerged in mud and water for periods of 4 to 7 



