220 



THE AMERICAN NATURALIST 



[Vol. LIII 



type known as the Broadleaf Mammoth was first observed 

 in 1906 in a selection line of Maryland Broadleaf begun 

 in 1904. Of 100 plants grown in 1906, five were typical 

 mammoth plants producing many leaves and showing no 

 tendency to bloom at the end of the season. Subsequent 

 generations of these plants were grown successively in 

 1907, 1908 and 1909, and all reproduced the characteristic 

 habits of growtli of thv orioinal parent isolated in 1906. 

 'rhi> niaimiiotli \y\n\ a- tlir name indicates, differed ma- 

 terially ill .-liajK' <if leaf from the better known Xarrow- 

 leaf Aiam.iiotli. 



The so-called Narrowleaf Mammoth appeared in 1907 

 in second generation plants of a cross made in 1905 be- 

 tween a F^roadleaf tyi)e and a Narrowleaf tyi)0 of ^lary- 

 land tobacco. From a single mammoth ])lant found in 

 l*.»ii7, 157 plants were grown in 190S. all of wliicli were 

 nianimoth i)lants. Two of these ]»lants which wore al- 

 lowed to grow until frost without topjiiiig had produced 

 109 and 111 lea\v>. ropeetlvely. witli no indication of 

 blooming. The Xarrowieaf Mainiiiolli has been propa- 

 li'ated from seed and m<.\vii on a cominercial scale in 

 Maiyland u). to the pivMMit tiiii.'. and under iionnal field 

 eoiuiition^ >till retain> it> eharaeteri>tie> of liiuli leaf num- 

 her and the non-1, loo, ni n- hahit. 



eialion plants of a ero^> nilw'le in IDo:) helween Maryland 

 15r<.adleaf aii<l the White I'.iirley vari.'lv of Kentneky. In 

 a riop ,,f :;().(inii to 4iM.(in plants l.nt <ine niainnioth j.lant 

 wa^ found, riifortunatelv. tlii^ plant wa< liarveMed in- 



all MaMinK.th typ.- vvhieli liav appear.-.l in the Tnited 



