Types of stem by Sarah Ashfaq , Botanist
- 1. Types of stems Presented by Sarah Ashfaq 1
- 2. Contents Introduction Definition of stem Characteristics of stem Types of stems Conclusion References 2
- 3. Introduction • A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, photosynthesis takes place here, stores nutrients, and produces new living tissue. The stem can also be called halm or haulm or culms. 3
- 4. Definition A main stem is the portion of the primary axes of the plant which develops from the plumule. 4
- 5. Characteristics of stem Terminal and axillary buds Green Nodes and internodes Positively phototropic Negatively geotropic Develops from the plumule of the embryo. Bears leaves, flowers and fruits Branches exogenously Ascending part 5
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- 8. Herbaceous stem Soft Green Bent Broken Vascular bundles No persistent woody stem Flexible Annuals, Biennials & Perennials 8
- 9. Examples Brassica napus Brassica rapa Poppy Carrot Parsnip Mint Ferns Grasses 9
- 12. 3. Fistular stem The vascular bundles and cellular tissue are sometimes developed in such a way as to form a circle, with a hollow in the centre, and thus give rise to what are called fistular or hollow stem. Internodes hollow 12
- 13. The stems of Oenanthe fistulosa (tubular water- dropwort) are hollow, with very thin walls. The stems of Bambusa vulgaris are hollow 13
- 14. 4. Solid stem Not hollow Hard Woody Woody stem growth occurs from a thin strip of cells called the cambium located just under the outer bark. Trees 14
- 15. 5. Jointed stem Stem are jointed with each joint forming a node. Swollen at the nodes Indian grass Andropogon gerardii 15
- 16. 6. Cylindrical stem Straight Round cylinder-like shape Erect Rosa indica Jasminum officinale Helianthus annuus 16
- 17. 7. Angular stem Having alternate ridges Furrows Not round in cross section Ocimum basilicum (Niazbo) 17
- 18. 8. Flattened stem Flat Plate like Ugly or attractive Including phylloclades Thick Fleshy Stored food Having chlorophyll Opuntia 18
- 19. 19. Glaucous stem Surface smooth More or less shiny Bluish green The stems of Bambusa vulgaris Glaucous stem and leaf stalks of Rubus occidentalis. The glaucous stem of Acanthocalycium glaucum 19
- 20. 20. Glabrous stem Surface smooth Not shiny No fine hairs Glossy Dryopteris cristata (crested wood fern). Brassica 20
- 21. 21. Succulent stem Thick Fleshy Store water Conduct photosynthesis Hoodia macrantha Opuntia Euphorbia royleana 21
- 22. 22. Spiny stem Spines Thorns on the surface For storage and protection To reduce water loss in arid conditions Duranta erecta stem Acacia stem Rosa indica stem 22
- 23. 23. Prickly Prickles (spine structure) Short Sharp woody projections that are derived epidermis. Ribes montigenum (mountain gooseberry) 23
- 24. Conclusion • Stems are the important structural axis of vascular plants. The stem of a plant is divided into three parts consisting of the node, the petiole, and the internode. They support leaves, fruits, flowers and produce new living tissues. Stems give accurate structures and foundations for plants. Stems are the main transportation routes of water from the roots to the leaves. 24
- 25. References • Greb, T., & Lohmann, J. U. (2016). Plant stem cells. Current biology, 26(17), R816-R821. • Laux, T. (2003). The stem cell concept in plants: a matter of debate. Cell, 113(3), 281-283. • Schweingruber, F. H., & Börner, A. (2018). The plant stem: a microscopic aspect. Springer. • Schweingruber, F. H., Börner, A., & Schulze, E. D. (2007). Atlas of woody plant stems: evolution, structure, and environmental modifications. Springer Science & Business Media. • Schulgasser, K., & Witztum, A. (1997). On the strength of herbaceous vascular plant stems. Annals of Botany, 80(1), 35-44. • Endress, P. K., Baas, P., & Gregory, M. (2000). Systematic plant morphology and anatomy‐50 years of progress. Taxon, 49(3), 401-434. 25
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