Stem and Secondary growth

Primary growth

growth in length; contains primary anatomy; happens firth

Secondary growth

Only in eudicots; growth in width; lateral meristems; contains secondary anatomy; all the wood in the tree is secondary xylem; has thick cellulose walls with lots of lignetn

Primary stem anatomy in Eudicots

Vascular bundles in a ring; clear pith and cortex; residual procambium

Pith

made up of parenchyma in the middle of the stem

Pith ray

Procambium

Dormant meristem; in-between xylem and phloem; activates to form 2nd growth

Primary growth in monocots

Scattered vascular bundles; no clear pith or cortex; no residual procambium and thus cant make wood

Why secondary growth

Not adequate for shrubs and trees with branching systems; dont provide enough support

Annuals

its life cycle happens in one year, stays over the winter as a seed

Biannuals

its life cycle is over 2 years

Herbecaous perenials

Around all year; Non-woody; areial shoots die in the winter; leave bulbs, tubes, and rhizomes

Palm trees

Are tall but still non-woody; have lots of lignin; lots of vascular bundles with lignin; abscise their leaves to decrease weight; not branching; proprots;

Who does secondary growth

Woody perennials; eudicots and conifers