stems
TRANSCRIPT
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.