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Buds and Leaves

Buds and Leaves. Understanding Vegetative Morphology. Buds. Buds are short embryonic stems. In angiosperms, buds are found at the nodes, in the leaf axil, or at the end of a stem. Buds are especially useful for identifying twigs in winter condition.

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Buds and Leaves

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  1. Buds and Leaves Understanding Vegetative Morphology

  2. Buds • Buds are short embryonic stems. • In angiosperms, buds are found at the nodes, in the leaf axil, or at the end of a stem. • Buds are especially useful for identifying twigs in winter condition. • Buds are protected by bud scales, a dense covering of hairs, and/or a sticky secretion.

  3. Axillary Buds

  4. Terminal Bud

  5. Bud Types • Accessory Bud • Axillary Bud • Flower Bud • Leaf Bud • Mixed Bud • Naked Bud • Pseudoterminal Bud • Superposed Bud • Terminal Bud

  6. Generalized Angiosperm Stem

  7. Lenticels and Leaf Scars • Lenticels are breathing pores in the young bark of a woody stem. Scattered lenticels dot the stem between leaf scars. • Leaf scars remain on a stem after the leaves have fallen. The circles within each scar are the severed ends of food and water-conducting bundles.

  8. Lenticels

  9. Leaf Duration • Leaves may function from a few days to many years, but most leaves function for only one or two growing seasons. • Deciduous leaves fall at the end of the growing season. • Evergreen plants are leafy throughout the year. • Marcescent leaves wither but do not fall during the winter or dry season.

  10. Marcescent Leaves • Many oaks, beeches, and hornbeams are marcescent. This may be an adaptation to protect winter buds from browsing animals. The dried leaves remaining on the plant are not very tasty!

  11. Leaf Arrangements

  12. Generalized Angiosperm Leaf

  13. Upper and lower leaf surfaces • Unifacial leaves lack any differentation between adaxial (upper) and abaxial (lower) leaf surfaces. • Bifacial leaves have definite differences between adaxial (upper) and abaxial (lower) leaf surfaces.

  14. Bifacial LeafPopulus alba L. Adaxial or upper surface Abaxial or lower surface

  15. Leaf Structure • A leaf with a single blade is termed simple. • A leaf with two or more blades, or leaflets, is said to be compound. • The distinction between simple and compound leaves can be made by locating an axillary bud: an axillary bud is subtended by the entire leaf and never by individual leaflets.

  16. Axillary Buds

  17. Leaf Examples

  18. Simple and Compound Leaves • Simple Leaves • a. Pinnate Venation • b. Palmate Venation • c. Parallel Venation • Compound Leaves • d. Pinnately Compound • e. Bi-pinnately Compound • f. Palmately compound

  19. Compound Leaf Examples

  20. Margin Patterns and Leaf Shapes

  21. Leaf Shapes

  22. Leaf Margins • As viewed from the side

  23. Venation Types • Primary vein (midvein) • The one most prominent vein in the leaf. • Secondary veins • Veins that branch from the primary vein. • Tertiary veins • Veins that link the secondaries.

  24. Venation Patterns • Percurrent or scalariform • Ladderlike • Reticulate • Netlike

  25. Pinnate Venation • Pinnate means ‘feather-like’

  26. Palmate Venation • Arise from one point at the tip of the petiole, like fingers of an outstretched hand.

  27. Leaf Apex Shapes

  28. Leaf Base Shapes

  29. Leaf Texture • Membranous – very thin • Chartaceous – papery in texture • Coriaceous – very thick

  30. Surface Texture Terms • Glabrous – lacking hairs. • Pubescent – with various hairs. • Glaucous – with a waxy covering. • Other Terms: • Arachnoid, canescent, hirsute, hispid, lanate, pilose, puberulent, scabrous, sericeous, strigose,tomentose,velutinous, villous.

  31. Selected Features of Hairs

  32. Liriodendron tulipifera L. • Simple leaf • Pinnate venation • Truncate apex • Cordate base • Long-petioled • Lobed

  33. Lonicera sempervirens L. • Perfoliate upper leaves • Ovate to oblong • Glaucous beneath on abaxial surface • Simple leaves

  34. Coleus x hybridus Voss. • Simple leaf • Margins serrate • Acute apex • Obtuse base • Pinnate venation

  35. Ricinus communis L. • Simple leaf • Palmately veined • Peltate • Long-petioled • 5-11 lobed

  36. Gymnocladus dioica • Bi-pinnately compound leaf • Leaflets entire • Pinnae in 3-7 pairs • Larger terminal ones with 3-7 pairs of ovate, acute leaflets to 3 inches long.

  37. Amorpha L. • Leaves odd-pinnate • Many leaflets • Leaflets entire • Compound leaves

  38. Populus alba L. • Simple leaf • Long petioled • Palmate venation • Lobed • Rounded or slightly cordate • Truncate base

  39. Taraxacum officinale • Leaves simple • Leaves oblong, spatulate, or oblanceolate. • Nearly entire to sinuate-pinnatifid. • Terminal segment largest.

  40. Pinus ponderosa • Leaves linear • Leaves needle shaped • Leaves usually in fascicles of 3. • 5 to 11 inches long.

  41. Cercis canadensis L. • Leaves simple • Leaves entire • Palmately veined. • Leaves broadly ovate to nearly orbicular. • Cordate at base. • Attenuate at apex

  42. Quercus macrocarpa Michx. • Leaves obovate • Leaves simple • Leaves pinnatifid with large terminal lobe. • Grayish-pubescent abaxial surface. • Deciduous

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