stems

Stems

Presented by : Geonyzl L. Alviola

Stem

Function for both supportive organs and conductive organ

It is a shoot associated with other plant organs like leaves, flower, fruit

It develops from the epicotyl of the embryo (in the seed)

Review on the parts of the plants:

1. Leaf primordium = an immature leaf of the shoot.

2. Node = the point of attachment of a leaf to a stem

3. Internode = the region between two adjacent nodes

Stem typesStem types

Modification of the stem would depend on the need of the plant to survive…

… like the animals it learns how to adapt.

Stem modifications for storage and protection

a. rootstock = a general term for an underground stem or shoot that later will give rise to aerial shoot.

= remain alive underground during harsh condition

Different types of RootstockDifferent types of Rootstock

Bulb – consist of small amount of vertical stem and a massive quantity of thick, fleshy storage leaves.

- most of them consist of concentric rings of scales attached to a basal plate.

Other bulbous plants

Daffodil Reticulate iris

2. Corm - formed from a swollen bases of stems.

- A corm consists of one or more internodes with at least one growing point.

Examples of CormExamples of Corm

Crocuses Gladioli

3. Caudex = the rootstock consist of a relatively undifferentiated but vertically oriented stem.

= generally called “fat plants”

Adenium obesum – family Apocynaceae (a relative of Calachuchi)

Other caudiciform plants

Ibervillea

Trochomeria

4. Rhizome= the stem is horizontal and underground with short internodes and bearing with scale-like leaves

ginger

Other rhizome plants

Johnsongrass Sorghum halepense

Cogon grassImperata cylindrica

5. Tuber = a thick under ground storage stem, usually not upright

= bearing outer buds

= lacking protective scales

Main plant parts are:haulm (foliage), tubers and roots.

Other Types of Stems

Stolon / runner = with long internodes just below the surface of the ground that typically terminating in a new plant

= use for propagation

Plants with Plants with stolonstolon

Bermuda grass (Cynodon dactylon).

Cladode

= resemble like a leaf

= a photosynthetic stem

= flatten in appearance

= reduce water loss

Thorn – is a sharp pointed stem.

- serve as protective structure of the plant.

Scape = “naked” , lacking vegetative leaves

= generally arising from basal rosette of vegetative leaves

= the stem-like, flowering stalk of a plant with radical or rosulate leaves.

Primula vulgaris Primula eliator

Culm = refers to the flowering and fruiting stems.

Tiller = are segmented, each possessing two part leaf

= involve in vegetative propagation

Pseudobulb

= short erect aerial storage or propagative stem

Stem Habit Describing the relative

position of the stem or shoot.

1.Caulescent – a plant with above ground stem. upright aerial stem with the leaves arising from all or some of the nodes on the above-ground stems

2. acaulescent – plants that 2. acaulescent – plants that bear photosynthetic leaves bear photosynthetic leaves at ground level.at ground level.

Yucca

3. Frutescent = a shrub with n umerous woody, 3. Frutescent = a shrub with n umerous woody, aerial trunksaerial trunks

Mimosa

Arborescent- tree like in appearance and size.