. Manuel de botanique agricole et pastorale, pour l'étude de l'effet préjudiciable et plantes utiles de pays et ferme. Bull. 70 Experimenl Station, Iowa State College, 1903, p. 337.) La grande marguerite {Icucanthemum pinnatifidnm chrysanthème).-Thestems de marguerite blanche sont en touffes de un à trois pieds de haut portant un chef blanc avec des fleurs marginales et jaune fleurs du disque. Le rootleaves sont dans une rosette et sont spatulés, pinnatifid. Les akènes, whichare trouvés en tant qu'impureté dans presque toutes les graminées, sont de couleur gris-noir à côtes sans andfinely la ppe])ers. Des semences propres onl&gt ;- devrait être semé. T

• Contributeur: The Reading Room / Alamy Banque D'Images
• ID de l’image: 2AG9WGJ
• Taille du fichier: 7,1 MB (296,5 KB Téléchargement compressé)
• Autorisations: Modèle - non | Propriété - non
• Dimensions: 2045 x 1222 px | 34,6 x 20,7 cm | 13,6 x 8,1 inches | 150dpi

Informations supplémentaires

Cette image appartient au domaine public, ce qui signifie que le droit d’auteur a expiré ou que le titulaire du droit d’auteur a renoncé à ses droits. Les frais facturés par Alamy couvrent l’accès à la copie haute résolution de l’image.

Cette image peut avoir des imperfections car il s’agit d’une image historique ou de reportage.

. Textbook of pastoral and agricultural botany, for the study of the injurious and useful plants of country and farm. Bull. 70 Experimenl Station, Iowa State College, 1903, p. 337.) Ox-eye Daisy {Chrysanthemum Icucanthemum pinnatifidnm).—Thestems of white daisy are tufted from one to three feet high bearing a headof flowers with white marginal ones and yellow disc florets. The rootleaves are in a rosette and are spatulate, pinnatifid. The achenes, whichare found as an impurity in nearly all grass seeds, are grayish-black andfinely ribbed without pep])ers. Clean seed onl>- should be sowed. Thedaisy field can ])e cleansed by short rotations, as the perennial roots are 252 PASTORAL AND AGRICULTURAL BOTANY turned out and killed by the plow. Mowing infested fields before theheads develop is another useful means of extermination (Figs. io6 and 107). Canada Thistle {Cirsium arvense).—Nearly all of the states have lawswhich make it an offense for their citizens to permit this weed to matureand scatter its seeds. It is a perennial propagated by seeds and rootstocks.The map shows its range (Fig. 108).. Fig. 108.—Map of the United States, showing the present distribution of theCanada thistle. The heavy line indicates the approximate southern boundary^of theweed; the shaded area shows where the plant is most injurious. (After Hansen, AlbertA.: Canada Thistle and Methods of Eradication. Farmers Bulletin 1002, 1918, p. 5.) Classification of Weeds Weeds are conveniently classified according to the duration of theirunderground parts into: 1. Annual weeds, or those which complete their growth and maturetheir seeds in one year. Such plants are easily destroyed by cultivation.Here belong ragweed, crabgrass, purslane, pigweed and Russian thistle. 2. Winter annuals. These plants drop their seeds in the fall whichgerminale and give rise to plants which hold through the winter, finallyproducing flowers and seeds in the spring. Such are the chickweed andshepherds i)urse. Here also

Recherche dans la banque de photos par tags

• bookcentury1900
• bookdecade1920
• booksubjectpoisonousplants
• librury