Fire weeds 



Raymond H. Torrey 



Commenting on the writer's note on Marchantia polymorpha, 

 after forest fires, Dr. G. E. Nichols, President of the Ecological 

 Society of America, Osborn Botanical Laboratory, Yale Uni- 

 versity, New Haven, Conn., writes: 



"The condition which you describe in your Torreya article is 

 a common one in northern Michigan, where I have conducted 

 a course on bryophytes at the University of Michigan Biological 

 Station for the past dozen summers. Except in dry sandy situ- 

 ations Marchantia is a common and abundant pioneer after for- 

 est fires. It frequently comes in on beds of matted down charcoal 

 on sites of former camp-fires. In fact, I commonly refer to 

 Marchantia and Funaria as 'fire weeds,' among the bryophytes." 



Funaria hygrometrica was also plentiful in the burned area 

 on Kittatinny Mountain, where I found the extensive Marchan- 

 tia colonies, and now that Dr. Nichols includes it among bryo- 

 phyte "fireweeds," I recall I have often seen it in spots that had 

 been burned, including places along railroads where old ties 

 had been burned. It would be interesting to list such pioneers 

 after fires, among all classes of plants. In our hardwood forests, 

 after a severe burning, a common one is Lechea intermedia ; and 

 on the Kittatinny location, A cnida tuberculata was very dense the 

 first year after the blaze and, now, in the second year, Pycnan- 

 themum incanum is common. There is some of the common Fire- 

 weed, Epilobium angustifolium, but it is not as dense as often 

 happens after burns in the North Woods. It seems to me that 

 lichens, especially these growing on earth, come back rather 

 slowly after burnings; although the crustose ones on ledges and 

 boulders, such as Rinodina oreina, Lecideas, Lecanoras and 

 Rhizocarpons survive pretty well. The Rock Tripes, Gyrophoras 

 and Umbilicarias, with their large foliose thalli, burn up when 

 caught in the fire belts, and are slow to reappear in such places. 



16 



