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Four functions of stems

Four functions of stems. Transport – water, minerals, sugars. Four functions of stems. Support – hold flowers and leaves up toward the sun. Four functions of stems. Storage – of extra food, and sometimes water (onion, garlic, sugar cane, cacti). Four functions of stems.

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Four functions of stems

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  1. Four functions of stems • Transport – water, minerals, sugars

  2. Four functions of stems • Support – hold flowers and leaves up toward the sun

  3. Four functions of stems Storage – of extra food, and sometimes water (onion, garlic, sugar cane, cacti)

  4. Four functions of stems • Food making – carry out photosynthesis – only can occur if stem is green (cactus, bamboo, garden veggies)

  5. Stem parts: EXCEPTION!! • Meristem– area (usually at the tip of the stem) where growth occurs

  6. Stem parts • Node – the area where a leaf is attached to a branch • Internode – the area between nodes

  7. Stem Parts • Cortex – storage tissue (same as the root) • Vascular bundle – same as a vascular cylinder. Contains xylem, phloem and cambium

  8. Stem parts • Bark – tough, protective tissue on the outside of woody trees • Pith - dead wood in the center of the tree

  9. Two basic types of stems: • Herbaceous – extremely dependent on water (turgor pressure) • Characteristic of monocots • Woody stems - ex – trees, vines, hedges, bushes • Characteristic of dicots

  10. Monocots vsDicots: • Monocots have their vascular bundles scattered throughout, while dicots have their vascular bundles in rings • Monocots tend to be herbaceous, while dicots are generally woody

  11. Annual rings • The result of the growth of xylem tissues. Year after year the wood produced by the cambium forms new layers. Springwood grows early in the season with many large xylem vessels. Summerwood grows later and has fewer and smaller xylem vessels. The differences in the texture of spring and summerwood are what produce the ring.

  12. Types of wood • Heartwood – hard, dark dead inactive wood in the center of a woody stem. Xylem and pith become plugged and ceases to function • Sapwood – live, active, functioning wood outside the heartwood.

  13. Sweeteners • Two major types of sweetener come from the stem of the plant – table and brown sugar (from sugar cane) and maple syrup

  14. Specialized types of stems • Stems used for food – white potato, rhubarb, onion, garlic, and sugar cane • Rhizome – thick, fleshy creeping underground stems that grow just below the surface of the ground (Iris) • Tubers – underground stems that are swollen with stored food, usually as starch (white potato) • Bulbs – stem is at the center, food is stored in layers of short, thick leaves that wrap around and protect the stem (onion and garlic) • Corms – similar to bulbs – thin scalelike leaves

  15. Misc. • Another food stem is asparagus • White potatoes are an underground stem called a tuber • Potatoes are the 4th most important food crop in the world and the only non grain in the top 5 • Potatoes have only been know outside of the America’s for the last 500 years • Potatoes were one of the most important food crops in Ireland until 1843. • The average family ate 40lb of potatoes a week

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