Stems Flashcards
What are the functions of stems?
Support plant parts in the right place
Transport of water/mineral nutrients towards the leaves
Transport the products of photosynthesis away from the leaves to other parts of the plant or from storage tissue especially in the spring
Storage
Growth
What is the function of the epidermis?
For protection
What is the function of vascular bundles?
For transport and support
What is the function of phloem?
To transport sugars such as glucose
What is the function of xylem?
To transport water and mineral nutrients
What is the function of the cortex?
Packing tissue and storage, gives limited support when turgid
What is the function of cambium?
Divides to produce new cells
What is the function of pith?
Packing tissue and storage
Xylem facts
Consists of vessels or vessel elements to conduct water and tracheids
Short wide cells perforated end walls to make continuous tubes
Strengthened with lignin
Dead at maturity with no nucleus which is killed
What are Tracheids?
More primitive cells in gymnosperms
What adaptations make tracheids successful?
They have pits in the side wall but no perforations in the end walls and they overlap to allow water to flow up the stem
They are also better suited to freezing and thawing
What does the phloem do?
Transports sugars away from leaves to areas of use and storage
Phloem key facts
They consist of companion cells and sieve tubes
The end walls have sieve plates containing pores to allow the sugars to be transported
Companion cells provide energy and instructions to the sieve tube cells
What’s the difference between sieve tubes and companion cells?
Sieve tubes have no nucleus and are dead whereas companion cells are alive with a nucleus
What stem tissues do monocots have?
Epidermis, vascular bundle, phloem, xylem and a cortex of parenchyma cells
What stem tissues do dicots have?
Epidermis, vascular bundle, phloem, xylem, cortex, cambium and pith
What can stems be modified for?
Climbing, stealing support from other plants, vegetative reproduction, perennation, photosynthesis, protection from grazing animals and food storage
What adaptations can stems have for climbing?
Twining stem, adventitious roots, tendrils and backwards prickles/ thorns
What adaptations can stems have for storage and vegetative reproduction?
Rhizome, bulb, corm, stem tuber or stolon
What are the components of a ring of cambium?
Primary phloem, vascular cambium, primary xylem, epidermis, pith and cortex
What are the components of a ring of cambium?
Primary phloem, vascular cambium, primary xylem, epidermis, pith and cortex
