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

Food making – carry out photosynthesis – only can occur if stem is green (cactus, bamboo, garden veggies)

Four functions of stems

Meristem – area (usually at the tip of the stem) where growth occurs

Stem parts:EXCEPTION!!

Stem parts

•Node – the area where a leaf is attached to a branch•Internode – the area between nodes

Cortex – storage tissue (same as the root) Vascular bundle – same as a vascular

cylinder. Contains xylem, phloem and cambium

Stem Parts

Bark – tough, protective tissue on the outside of woody trees

Pith - dead wood in the center of the tree  

Stem parts

Herbaceous – extremely dependent on water (turgor pressure)◦ Characteristic of monocots

Woody stems - ex – trees, vines, hedges, bushes◦ Characteristic of dicots

Two basic types of stems:

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

Monocots vs Dicots:

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.

Annual rings

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.

Types of wood

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

Sweeteners

Brazil 645,300,182

 India 348,187,900

 People's Republic of China

124,917,502

 Thailand 73,501,610

 Pakistan 63,920,000

 Mexico 51,106,900

 Colombia 38,500,000 F

 Australia 32,621,113

 Argentina 29,950,000

 Philippines 26,601,400

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

Specialized types of stems

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

Misc.