436 IOWA ACADEMY OF SCIENCE 



WEED FLORA. 



Of all the weeds that occur in the area covered by this paper, 

 there is one that stands out pre-eminent as causing more trouble 

 than all others combined. That species is the common chick- 

 weed, Alsine media. The spurry (Spergula arvensis) probably 

 would rank second in importance with sorrel (Rumex acetosella) 

 third. The following list includes all the species that have 

 as yet become important in this habitat group. It includes 

 several introduced species as well as a few that are included in 

 other lists. 



Brassica arvensis Montia fontana 



Bursa sp. Plantago major 



Cardamine sp. Ranunculus repens 



Cerastium spp. Rumex obtusifolius 



Epilobium angustifolium Rumex occidentals 



Epilobium affine Senecio vulgaris 



Matricaria matricaroides Taraxacum officinale 



Mimulus langsdorfii Veronica americana 



Monarda sp. Veronica serpyllifolia 



In addition to the foregoing, the following have been found, 

 having been introduced with seed, packing, etc. They are, as 

 yet, quite rare and of almost no importance from an economic 

 standpoint. Some may in time become established. 



Agrostemma githago Saponaria Vaccaria 



Anthemis cotula Sisymbrium officinale 



Camelina sativa Solanum nigrum 



Cbenopodium album Soncbus asper 



Polygonum convolvulus Vicia angustifolia 

 Polygonum pennsylvanicum 



Mention might also be made of a parasite, Razoumofskya 

 douglasii tsugensis (Plate XXIV), which causes much damage 

 to the Western hemlock (Tsuga Jietcropltylla) . It attacks the 

 branches causing them to enlarge and proliferate. Scarcely a 

 host tree of any size is free from the parasite. 

 ECONOMIC PLANTS. 



The economic plants of Alaska naturally arrange themselves 



in three groups: 1. Forest trees. 2. Grasses and forage plants. 



3. Fruit-bearing plants. These will now be taken up in their 



order. 



FOREST TREES. 



Of all the plants native to the coast region of Alaska, the 

 Sitka or Tideland spruce (Picea sitchcnsis) is by far the most 



