120 ORIGIN 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 184;8.^ He clearly showed the differences 

 between Linum usitatissirauniy L. huTnile, and L. angus- 

 tifoliwm, which were little known. Afterwards Heer,^ 

 when making profound researches into ancient cultivation, 

 went again into the characters indicated, and by adding 

 the stud}^ 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 different forms. I give a translation of 

 his Latin summary of tlie characters, only adding a name 

 for each distinct form, in accordance with the custom of 

 botanical works. 



Linum usitatlssimum. 



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

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

 terminating in a point, a. 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. Linum 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 iLijemale roma- 

 nmn. In German, WinteHein. 



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. Linum amhiguum, Jordan. 



4. An gust i folium (narrow-leaved). Root annual or 



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



* Heer, Die Pflanzen der Pj'ahlhauten, in 4to, Ziiiich, 18G5, p. 35; Ueher 

 den Flachs und die Flacliskultur, in 4to, Ziirich, 1!S7-. 



