128 Floristik, Geographie, Systematik etc. 



Adamson, R. S., An Ecological Study ofaCambridge- 

 shire Woodland. (Linn. Soc. Jour. Bot. XL. p. 339—384. PI. 

 12—17. 1 flg. 1912.) 



The observations were made in Gamlingay Wood, 15 miles 

 west of Cambridge. The wood is on a ridge of Boulder Clay 

 (66 metres ab. s. 1.) over Gault and Lower Greensand, but pre- 

 sents two distinct soil-types, a heavy calcareous clay and a non- 

 calcareous loam. The Vegetation is almost natural and is resolved 

 into: ä) Ash-Oak association on calcareous; b) Oak wood association 

 on the loam. Climatic details, rainfall, temperature and wind are 

 given for the locality. The calcareous soil in winter becomes muddy 

 and water collects in hollows, while in summer it is hard and cracks; 

 the non calcareous loam remains drier on the surface and does not 

 harden and crack so much in summer. The soils were examined in 

 considerable detail: mechanical analysis, CaC0 3 , water-content and 

 temperature. The factors light and evaporation were also investigated. 

 The type^of wood is "coppice with Standards", thatis all except a few 

 trees are removed at short periods so that the ground Vegetation is 

 exposed to considerable ranges of light, etc. The dominant tree, 

 Quercus Robur (pedunculata) with absence of Q. sessiliflora, repro- 

 duces naturally and no records of planting are known. Ulmus (3 

 forms), Populus tremula, and Betula (on loam only) are common. 

 As a result of periodic cutting these trees with Fraxinus excelsior 

 and Corylus are largely present as "pseudo-shrubs". The distribution 

 of trees and shrubs are shown (PI. 12), and on a corresponding 

 map the distribution of prominent plant-societies of the ground 

 Vegetation. These societies are illustrated by photographs(Pl. 14 — 17). 



The plant-societies of the two associations are controlled mainly 

 by soil-moisture, the intensity of light, and the rate of evaporation. 

 Light was estimated by a Photographie actinometer; evaporation 

 was measured by Yapp's evaporimetersand the records for a series 

 of these instruments is given. The main results are: 



A. The calcareous soil (Ash-Oak) societies are dominated by 

 Spiraea Ulmaria, either pure or mixed with Deschampsia caespitosa, 

 and by Mercurialis perennis. Each society shows local variations 

 depending largely on light and soil-moisture. The main features ot 

 each society: 



I. Spiraea, society has a ränge of light- values of "005 — *01. and 



a high water-content, summer average 36 — 43 p.cent. 

 II. Spiraea- Deschampsia soc, water-content as I, light '03 — '6. 



III. Mercurialis soc, varying quantity of light, summer w — c. 

 22—26 p.cent. 



IV. Fragaria vesca soc, intermediate between II and III. 



B. Non-calcareous (Oak wood) societies: 



I. Pteris aquilina — Holcus mollis soc, summer water-content 



19—22 p.cent.; soil a heavy loam. 

 II. Holcus mollis soc, summer w — c 17 — 19 p.cent.; soil rather 



more sandy. 

 There is a list of the flowering plants and a bibliography. 



W. G. Smith. 



Ärcangeli, J., Note on Victoria regia, Lindl. (Scott, bot. Review 

 I. 2. p. 115—116. 1912.) 



Records growth, flowering and seeding of this plant at Pisa 

 in a greenhouse with solar heat only. The species grows in pools 



