120 OEIGIN OF CULTIVATED PLANTS. 



In order to understand the difficulties which it 

 presents, we must first ascertain what nearly allied forms 

 authors designate — sometimes as distinct species of the 

 genus Linum, and sometimes as varieties of a single 

 species. 



The first important work on this subject was by 

 Planchon, in 1848.^ He clearly showed the differences 

 between Linwm v^itatissimum, L. humile, and L. angus- 

 tifolium, which were little known. Afterwards Heer,^ 

 when making profound researches into ancient cultivation, 

 went again into the characters indicated, and by adding 

 the study of two intermediate forms, as well as the com- 

 parison of a great number of specimens, he arrived at the 

 conclusion that there was a single species, composed of 

 several slightly difierent forms. I give a translation of 

 his Latin summary of the characters, only adding a name 

 for each distinct form, in accordance with the custom of 

 botanical works. 



Linum usitatissimum. 



1. Annuum (annual). Root annual; stem single, 

 upright ; capsules 7 to 8 mm. long ; seeds 4 to 6 mm., 

 terminating in a point, o. Vulgare (common). Capsules 

 7 mm., not opening when ripe, and displaying glabrous 

 partitions. German names, Schliesslein, Dreschlein. 

 /3. Humile (low). Capsules 8 mm., opening suddenly when 

 ripe; the partitions hairy. Linumi humile, Miller; L. 

 crepitans, Boninghausen. German names, Klanglein, 

 Springlein. 



2. Hyemale (winter). Root annual or biennial ; stems 

 numerous, spreading at the base, and bent; capsules 

 7 mm., terminating in a point. Linum, hyemale roma- 

 num. In German, Winterlein. 



3. Amhiguum (doubtful). Root annual or perennial ; 

 stems numerous, leaves acuminate ; capsules 7 mm., with 

 partitions nearly free from hairs ; seeds 4 mm., ending in 

 a short point. Linvmv amhiguum,, Jordan. 



4. Angustifolium (narrow-leaved). Root annual or 



' Planchon, in Hooker, Journal of Botany, vol. vii. p. 165. 

 ' Hecr, Die Pflanzen der P/ahlbauten, in 4.to, Ziirich, 1865, p. 35 j Uebei 

 den Machs und die Flaclislmltiir, in 4to, Zurich, 1872. 



