30 Floristik, Geographie, Systematik etc. 



here by methods which rank as pioneer in plant ecology. The 

 coastal shingle bank at Blake ney Point (Norfolk), and other 

 banks, exhibit a distribution of Suaeda apparentW erratic until 

 examined by the methods used here. This bank, like others, is 

 subject to change from,a longitudinal drift alongshore, and also to 

 effects produced when on shore gales carry shingle over the crest 

 and down the lee slope to encroach on the salt marsh or estuary 

 on the landward side of the bank. By means of scale-charts it is 

 shewn that Suaeda is mainly distributed on the lee slope, and that 

 in favourable places it forms a triple zone: one near the crest, one 

 lower down just along the upper limits of the shingle fans, and a 

 ihird on the margins and slopes where the fans abut on the mud. 

 The third zone is where Suaeda is mainly established from seed 

 deposited with tidal drift from the marshes; the protection from this 

 drift is regarded (from comparison with other banks), to be an 

 essential factor, and careful examination shows that seedlings only 

 rarely become established on higher parts of the bank. A diagram- 

 map illustrates the distribution of Suaeda, and its presence or ab- 

 sence are considered in relation to the various types of inlet and 

 margin presented on a shingle bank; the necessary conditions for 

 establishment of Suaeda are facilities for introduction of seed to the 

 lee fringe (inoculation), and stability of the fringe during establish- 

 ment (stability). The primary zone is gradually overwhelmed by 

 fresh movements of shingle, but Suaeda responds by continually 

 growing up to the surface. The shingle bank thus travels through 

 the primary zone, and Suaeda mounts the lee slope. The zonation 

 corresponds to periods of dormancy of the bank, most marked 

 above the fans, and again near the crest; these phases are illustrated 

 by Charts based on measurement, also by photographs. Where 

 Suaeda is established, the plants cause fresh shingle thrown over 

 the crest by gales to foUow definite lines or Channels corresponding 

 to gaps in the crest zone of Suaeda, hence the plant has considerable 

 influence on the dynamics of a shingle bank (see Charts). A descrip- 

 tion of the species as distributed on the Chesil Bank (Dorset) gives 

 confirmatory evidence since the conditions there are different. The 

 observations are considered in relation to stabilising beaches by 

 planting, and it is deduced that the mobility of shingle on the lee 

 slope can be reduced. with a consequenf elevating of the protecting 

 crest by a scheme of afforestation with Suaeda. The plate includes 

 13 excellent photographs of Suaeda Vegetation. W. G. Smith. 



Pammel, L, H., The weed flora of Iowa. With the colla- 

 boration of Charlotte M. King, J. N. Martin, J. C. Cun- 

 ningham, Ada Hayden, and Harriet 5. K eUogg. (Bull. 

 n". 4, Iowa Geol. Survey. Des Moines, 1913.) 



An octavo of XIII, 912 pages, with 570 illustrations, The text is 

 divided into thirteen chapters, of which the first, a descriptive 

 manual, occupies 404, the sccond. on the general character of seeds, 

 requires nearly an additional hundred and the third, on the micros- 

 copical structure of some weed seeds, eighty-five. The remaining 

 chapters, though of considerable lenght, are much shorter and 

 refer to the morphology of flowers and leaves, the scattering of 

 weeds, roots and root-stocks, the number and kinds of weeds on 

 different soils, injuriousness of weeds, weed migration, medicinal 

 weeds, phenology of weeds, weed and seed laws, and a history 



