70 Floristik, Geographie, Sj'stematik etc. 



are usually hydrophytic or xerophytic, and the general trend of 

 Vegetation is from diversity to uniformity, the final formation being 

 as near the mesophytic, as the climate of the region will allow. 

 After a sketch of the development of dynamic plant geography from 

 King in 1685 to modern plant geographers, Cowles proceeds to 

 consider the delimitation of successional factors, of which no systematic 

 attempt has been made to group them in an analytic manner from 

 the Standpoint of their causation. 



Regional successions, as related to changes during the several 

 geologic epochs, are considered as due to secular changes of climate 

 which are too slow to be attested in a human life time. Successions 

 due to changes in topography are described under the caption, 

 topographic successions, while biotic successions are presented first 

 as to their general features, then as related to the humus complex 

 (water, soil organisms, toxicity of soil, food, temperature, aeration;. 

 The light relationship is next considered together wich the biotic 

 influences of plant invasion and man. In conclusion, the author 

 states that vegetative cycles are not of equal value. Each climatic 

 cycle has its vegetative cycle; each erosive cycle within the climatic 

 cycle has its vegetative cycle; and biotic factors institute other cycles, 

 quite independently of climatic or topographic change. A biblio- 

 graphy follows. J. W. Harshberger. 



Druce, G. C, The Botany of the Fen-land of Northampton- 

 shire. (Jour. Northants Nat. Hist. Soc. XV. N°. 119, p. 100-105. 1909). 



Notes made during a series of excursions, special attention 

 being given to aquatic plants in the ditches which drain theFenland, 

 and to weeds of the cultivated fields. A list of 100 species is given. 

 A new British species of Zannichellia was found with fruits slightly 

 stalked and the Upper and lower sides armed with short spines, 

 the habit of the plant is slender and the leaves narrow; the identi- 

 fication is Z. gibberosa Reichb. [syn. Z. pedunculata Reichb. var. 

 gibberosa (Reichb.) or Z. maritima Nolte. var. gibberosa (Reichb.)]. 



W. G. Smith. 



Erdner, E., Bayerische Brombeeren. (Mitt. ba}'-er. bot. Ges 

 II. 18. p. 303—307. 1911.) 



Viele kritische Bemerkungen über gefundene Ritbus- Arten, die 

 von W. O. Focke revidiert wurden. Rubus Kolbii Erdner umfasst 

 alle + samenbeständigen Mittelformen zwischen R. caesius und 

 tomentosus. Verf. warnt vor Ueberschätzung der Brombeer-,, Arten" 

 und deren Konstanz, da dieselben an systematischem Werte denen 

 anderer Gattungen meist weit nachstehen. Wenn gewisse ältere und 

 jüngere Botographen glauben, jeden einzelnen Zweig bestimmen zu 

 können und eventuell neu benennen zu müssen, so ist dies eine 

 ganz zwecklose Spielerei. Matouschek (Wien). 



Fröhlich, A., Der Formenkreis der Arten Hypericum Per- 

 foration L. , H. maculatum Cr. und H. acutum Mnch. nebst 

 deren Zwischenformen innerhalb des Gebietes von 

 Europa. (Anz. kais. Akad. Wiss. Wien, math.-nat. Klasse. IX. p. 

 135—137. 1911.) 



1. Hypericum Desetangsii Lamotte ß imperforatum Bonnet wird 



