Floristik, Geographie, Systematik etc. 



317 



Raunkiaer, C, Om Bladstörrelsens Anvendelseidenbio- 

 logiske Plantegeografi. [On the use ofleaf-size in bio- 

 logical phytogeography], (Botanisk Tidsskrift. XXXIV. 5. 

 p. 225 — 237. 5 tables. 1 plate. Köbenhavn, 1916.) 



The Alpha and Omega of science being comparison it is neces- 

 sary to make phenomena comparable, and this is done in measuring 

 and counting them. Now in xeromorphous plants there is a mul- 

 titude of different adaptations whose values are very difficult to 

 estimate but whose degree must be determined it' an exact com- 

 parison of different xerophilous plant communities shall ever be 

 attained at. 



Of the adaptations to drought, reduction of leaf-size is very 

 common and also easy to examine and to measure. In measuring 

 and comparing leaves a difificultj'' is met in incised leaves: what is 

 the Unit here? For composite leaves comparison learns that the 

 leaflets are of about the same size as the entire leaves of other 

 trees in the same formation, so that nature seems to regard, as it 

 were, the leaflet as unit. For laciniate and pinnatisect leaves there 

 is no clear evidence. Hence, it is necessary to keep them apart 

 and determine their frequency in each formation, and the same 

 may be done for the composite leaves. For entire (and lobate) 

 leaves the author establishes 6 classes, viz.: Leptophyllous, under 

 25 mm2, Nanophyllous, 26—225 mm2, Microphyllous, 226—2025 mm2, 

 Mesophyllous, 2026—18225 mm2, Macrophyllous, 18226—164025 mm^, 

 and Megaphyllous, above the last named size. 



These classes were made by estimate in comparing a great 

 many different leaves; the limits thus approximately found were 

 afterwards fixed, each of the limiting numerals being a multiple by 

 9 of the previous one. The four smaller ones are figured on the 

 plate, the examination of which immediately shows the size-class to 

 which a leaf belongs 



In Order to demonstrate the use of these size-classes Raun- 

 kiaer gives analyses of four plant-formations, viz. 1) a Danish 

 Calluna-heath , 2) a Maquis from southern France {Erica multiflora 

 formation), 3) a mountain Maquis in northeastern Spain {Arbutus 

 TJnedo -|- Quercus coccifera formation), and 4) a Thymus-he^cVa. in 

 interior northern Spain {Thymus hiemalis formation). Dominating 

 in all of them are evergreen Nanophanerophytes and Chamaephytes 

 with entire or lobate leaves; of other types, 1) has two rare spe- 

 cies, 2) none. — The analyses are given in four tables where the 

 species, their growth-forms (in Raunkiaer's sense) and leaf-sizes 

 are put down. The final comparison shows the foUowing percentage 

 of leaf-sizes based upon frequency of species: 





Per Cent distribution in leaf- 

 size classes, based upon fre- 

 quency of species. 





microph. 



nanoph. | leptoph. | 



Thymus hiemalis form. 







100 



Callima vulgaris form. 





7 



93 



Erica multißora form. 





21 



79 



Arb. Unedo -f- Qu. 

 coccifera form. 



59 



27 



14 



The first of these four formations has the lowest plants, the 



