986 



The characteristic higher piants ^ of this formation are: Sediim 

 rhodiola, Oxyria digijna , Anneria, Plantago maritima , Cochlearia 

 officinalis (formå), Saxifraga atespitosd, S. opposiiifolid ; less important 

 are: Draba hirta, Sileiie acaulis, Alchimilla alpina, A. faeroensis, Jnn- 

 cus trifidns, Pohjpodinm vnlgare, and the grasses, Poa glanca and 

 Festnca ruhra.^ 



All the dicotyledons of this gioup have certain features in com- 

 mon. They are all spot-bound and have a vigorous tap root ex- 

 tending far down into the fissures, thus anchoring the plant and 

 securing it against mechanical injury; the tap-root is also able to 

 secure water from a great depth, and in some species probably 

 serves also as a reservoir for storage of vs^ater and food. Another 

 feature common to almost all, is that they are decidedly xerophyles; 

 many are succulent, some have small leaves, and others are closely 

 beset with hairs (Saxifraga caespitosa, Draba hirta and parts of the 

 two species of Alchimilla). The majority are »rosette-plants«, but 

 as exceptions to this rule we have Sednm rhodiola and Saxifraga 

 oppositifolia. 



Among the characteristic monocotyledons, Poa glaiica is dis- 

 tinctly a cæspitose grass; Fes/«ca nzfcra has subterranean stolons and 

 forms a close grass-sward (see Fig. 188), Juncns trifidns has a hori- 

 zontal subterranean rhizome, with shortjointed shoots closely set to- 

 gether, so that from a biological point of view the plant is spot- 

 bound. Polypodinm vnlgare has also a horizontal rhizome. This fern 

 and the grass Festnca rnbra are species also found in other for- 

 mations, the latter occurring almost everywhere in all kinds of ha- 

 bitat and in many varying forms; we may therefore be justihed in 

 omitting these from the more typical chomophytes. It may thus 

 be said, that all chomophytes are rosette-forming or tufted piants, 

 mostly with a long, vigorous tap-root. 



As these piants have no organs for vegetative propagation, their 

 multiplication is entirely dependent on seed, and accordingly they 

 are found to flower and fruit abundantly. Most of the s[)ecies 

 mentioned, have a comparatively early flowering period and mature 

 their fruits in good time. A large majority are entomophilous or 



^ The mosses have not beeii taken into consideration in this and tlie two 

 following formations. 



^ The rarer species, — Dryas octopetala, Sali.v glaiiat and Papaver radicatiim 

 — ma}' perhaps be included here; although the}^ are not strictly chomophj'tes 

 in countries, where common. 



