LIFE FORMS AND SYNECOLOGICAL UNITS 



291 



the ground. Here belong such plants as Cirsium arvense and Aconitum 

 napellus (Fig. liSh). 



VII. HEMiCRYPTOPHYTES (Fig. 1486 to e) : plants with perennial shoots and 

 buds close to the earth's surface. They often have the protection of a covering 

 of dead and living scales, leaves, or leaf sheaths. The class is marked by great 

 variety in the development of the vegetative shoots. Numerous cryptogams are 

 to be counted among the hemicryptophytes. 



1. Hemicryptophyta thallosa (attached thalloid plants): spreading mats of 



algae or fungi, closely attached to the substratum. They are filamentous, 



sod-forming, crustose, clump forming, or jelly-like. They include: 



a. Attached algae: such as the epilithic forms appearing as ink lines on 



limestone rocks, the green coverings on bark {Pleurococcus, Protococcus) , 



and gelatinous algae like Nostoc.^ 



Fig. 148.— Types of life forms including chamaephytic creeping herbs (a) Carcx 

 limosa; hemicryptophytes {h-c); climbers (6) Coronilla; rosette plant (c) ; scapose plant 

 (rf); tufted plant (e) ; bulb geophyte (/) ; rhizome geophyte (g); tuber geophyte (h); 

 and therophyte (i). 



b. Crustose lichens: such as Acarospora and Opegrapha. 



c. Thalloid bryophytes: liverworts, such as Marchanlia, Pellia, Clevea, and 

 Grimaldia. 



2. Hemicryptophyta radicantia^ (rooted hemicryptophytes). 



a. Hemicryptophyta caespitosa (tussock plants): with renewal buds sur- 

 rounded and protected by a tliick strawlike cover of old leaf sheaths. 

 Tussock plants are common in moor regions and especially in the north 

 and in mountains above the timber line, where tussock species of Festuca, 

 Sesleria, Carex, and Nardus take an important part in the sod and soil 

 formation of the alpine levels of mountains. Carex elata, with huge 

 tussocks, up to one meter high and equally wide, is a main cause of land 

 formation in our ponds and lakes. Giant tussocks are formed by Poa 

 foliosa in New Zealand and by P. flabcllala in South Georgia and upon 

 the Falkland Islands. 



b. Hemicryptophyta rosulata (rosette plants) : mostly low herbs with radical 

 leaves arranged in a rosette and a leafless stalk, which bears the flowers. 

 Species of Fragaria, Viola, Primula, Genliana, and Bellis are found among 



1 Algae whose ramifications enter the substratum (Trentepohlia, etc.) occupy 

 a transitional stage. 



2 May be designated as Euhemicryptophytes. 



