Piante e loro modi in Sud Africa . Esaminare le foglie giovani date. Si sono intrecciate invece di arrotolate. Quando le foglie sono ramificate, la ramificazione dipende dalla ramificazione delle vene. In alcune foglie c'è una vena centrale forte, da cui si diramano altre vene su entrambi i lati, le pinne si diramano dal quillo di una piuma. Tale venationis denominato pinnate. O più vene forti possono iniziare dalla base o dalla parte inferiore della foglia, e la venazione è saidto essere palmate (mano-come). Nella maggior parte dei dicotiledoni le vene prominenti si uniscono ciascuna in modo da formare una rete irregolare; le veneins terminano con fre

• Collaboratore: The Reading Room
• ID dell’immagine: 2AXF659
• Dimensioni dei file: 7,1 MB (257,3 KB Download compresso)
• Liberatorie: Modello - no | Proprietà - no
• Dimensioni: 1679 x 1487 px | 28,4 x 25,2 cm | 11,2 x 9,9 inches | 150dpi

Altre informazioni

Questa foto è un'immagine di pubblico dominio, il che significa che il copyright è scaduto o che il titolare del copyright ha rinunciato a tale diritto. Alamy addebita un costo per l'accesso alla copia ad alta risoluzione dell'immagine.

Questa immagine potrebbe avere delle imperfezioni perché è storica o di reportage.

Plants and their ways in South Africa . ded. Examine young date leaves. They areplaited instead of rolled. When leaves are branched, the branching depends uponthe branching of the veins. In some leaves there is a strongcentral vein, from which other veins branch on either side asthe pinnae branch from the quill of a feather. Such venationis termed pinnate. Or several strong veins may start fromthe base or lower portion of the leaf, and the venation is saidto be palmate (hand-like). In most dicotyledons the prominent veins join each otherso as to form an irregular network ; the veinlets end freely and 48 Plants and their Ways in South Africa the margins are often notched. In monocotyledons theyusually run more or less parallel, the veinlets join near themargin which is usually entire. Simple leaves are sometimescut. They are called lobed, parted, or divided, according tothe depth of the incisions. The leaflets of a compound leaf are attached by a littlehinge or joint. Lebeckia linearifolia, E.M. has but one leaflet. ^^^^UmUA. Fig. 54.—Banana leaves torn by the wind. Fig. 55.—Compound leaf of Orange with one leaflet. The hinge at the base tells that it is a compound leaf which hasbecome reduced to a single leaflet. Other Lebeckias haveseveral leaflets. The same is true of the Orange and Lemonleaf. The trifoliate Orange has three leaflets. The Arrangement of Leaves on the Stem.—Wehave seen that leaves are not well developed when coveredfrom the light. Light as well as air is necessary for greenleaves to do their work of making food for the plant. Too A Study of Leaves 49 much light, however, is injurious. If we bear in mind thesetwo facts, it will help to explain the meaning of the forms andarrangements. Leaves also transpire; but the plant must not lose toomuch water. To be able to meet all these conditions, it isnot surprising that we find such a variety of forms and arrange-ments.

Parole chiave associate all'immagine

• bookcentury1900
• bookdecade1910
• booksubjectplants
• bookyear1915