Arctic Plants: Concluding Remarks 129 b 



CHAPTER III. CONCLUDING REMARKS. 



The vegetative structures described in the preceding pages are those 

 exhibited by arctic plants in general, and the examples cited are from material 

 gathered on the north coast of this continent. As a feature especially character- 

 istic is the persisting primary root, frequently developed as a thick fleshy tap- 

 root, and well represented in various genera, as for instance: Rumex, Papaver, 

 Parrya, Oxytropis, Campanula, Artemisia, etc. Or the root-system may be 

 represented by a series of secondary, slender roots proceeding from a horizontally 

 creeping rhizome, as for instance in Saxifraga aestivalis, Pedicularis sudetica, 

 Lagotis, Valeriana, Arnica, Saussurea, etc. The tuberous roots so characteristic 

 of Ficaria and Corydalis are rarely observed in these regions; however, Ficaria 

 does occur in arctic Europe, and Kjellman discovered the tuberous-rooted 

 Corydalis pauciflora Pers. at Port Clarence. 



Then with regard to the subterranean stem, this may be quite thick and 

 sparingly branched, lacking the slender, horizontally creeping ramifications 

 known as stolons; this simple structure is found in Polygonum viviparum-, ^ 

 Lagotis, Valeriana, Arnica, and Saussurea. 



More frequently the rhizome develops stolons, often attaining a consider- 

 able length. This structure is exceedingly well represented by many Gramineea, 

 Cyperaceae, and by a number of species belonging to different genera of the 

 Dicotyledons, for instance: Polygonum Bistorta, Oxyria, Stellaria longipes, 

 Merckia, Halianthus, Anemone parviflora and A. Richardsonii, Ranunculus 

 lapponicus, Polemonium, various species of Pedicularis, Petasites, etc. 



Aerial stolons are, of course, seldom met with but they are, nevertheless, 

 profusely developed in Glyceria vilfoidea. Ranunculus Cymbalaria, Saxifraga 

 flagellaris, and Androsace Chamaejasrne. 



Pseudo-rhizomes, we have seen, are not infrequent; they are characteristic 

 of several members of the Caryophyllaceae, Cerastium, for instance, also Cham- 

 aenerium, various Papilionaceae, etc. 



The bulb so characteristic of the Liliaceae, is found in Lloydia, in Alliurn 

 sibiricum, and among the Melanthaceae in Zygadenus glaucus. However, this 

 type of stem recurs in some of the dicotyledonous genera, notably in Saxifraga 

 cernua and ;S. rivularis, or as a secondarj^ structure caused by transformation of 

 flowers in Saxifraga cernua, S. stellaris forma comosa, Polygonum viviparum, 

 and to som e extent in the viviparous Aira alpina and Festuca ovina. 



As to the stem above ground we notice quite a considerable variation 

 among the herbs ranging from the simple leafless scape emerging from a rosette 

 of leaves in Primula, Dodecatheon, Ranunculus Cymbalaria, Saxifraga aestivalis, 

 to the amply ramified shoots of all those species which have the cushion-like 

 structure known so well from these regions. As examples may be mentioned 

 Silene, Douglasia, Phlox, Saxifraga tricuspidata, S. bronchialis. Chrysanthemum 

 integrifolium, Oxytropis arctobia, 0. nigrescens, etc. 



Among the woody plants there are several, more or less prostrate shrubs, 

 represented by the willows, by Betula, Empetrum, Dryas, Vaccinium, Rhododen- 

 dron, Loiseleuria, etc., and even trees are not absent as the presence of Picea 

 canadensis testifies. 



Concerning the foliage, there are many different types from simple, entire 

 to lobed or cleft, or compound: Papaver, Artemisia, Polemonium, Selinuni, the 

 Papilionaceae, Rosaceae, etc. Glabrous and hairy leaves are almost equally 

 common, but succulent leaves are seldom met with; Rhodiola may be mentioned 

 as an instance. In several of the herbs the leaves persist throughout the winter, 

 and several of the shrubs are evergreen, for instance: Dryas, Empetrum, the 

 Ericaceae, etc., not speaking of Picea. 



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