Types of Stems

(a) Herbaceous stems

(b) Woody stems

(a) Herbaceous stems

The stem tissue is relatively soft and easily crushed.

Plants with herbaceous stems are usually small and do not grow tall.

If they deprived off water, the stem wilts, bends and may even collapse altogether.

Mechanical strength in herbaceous stems is directly related to the turgor pressure of the living cells (parenchyma).

Other herbaceous plants obtain support by twining round other plants e.g. passion fruit stems and morning glory.

Tendril

Others support themselves by use of tendrils e.g. pumpkin

(b) Woody stems

Possess support tissues whose cells have stiff, thickened or lignified walls. Hence referred to as strengthening tissues.

The strengthening tissues include; collenchyma, sclerenchyma and xylem (vessels and tracheids).

Even when dry, these cells remain strong and maintain their shape.

The stems grow both in height and diameter.