Stems Flashcards
What distinguishes stems from roots?
Stems typically have a thick cuticle on the epidermal cells, nodes, internodes, and vascular tissues (xylem and phloem).
What is a node?
A node is the area of a stem where a leaf or leaves are attached.
What is the function of the apical meristem in stems?
The apical meristem contributes to the stem’s growth in length by producing primary tissues.
What are the three primary meristems that develop from the apical meristem?
1) Protoderm (epidermis), 2) Ground meristem (pith and cortex), 3) Procambium (primary xylem and phloem).
What is transpiration, and how does it relate to xylem transport?
Transpiration is the process of water moving up through the xylem from roots to leaves, driven by evaporation.
How is phloem transport different from xylem transport?
Phloem transport moves food (sucrose) in any direction from a source to a sink, unlike xylem which only moves water upwards.
What are the differences between herbaceous and woody dicotyledonous stems?
Herbaceous stems are green and primarily consist of primary tissues, while woody stems develop secondary xylem (wood) and have secondary growth.
What are specialized stems and how are they identified?
Specialized stems differ from typical stems but have nodes, internodes, and axillary buds, distinguishing them from roots and leaves.
What is a rhizome?
A rhizome is a horizontal stem that grows below ground, producing adventitious roots and having nodes and internodes.
How do runners differ from rhizomes?
Runners grow above ground and have long internodes, while rhizomes grow below ground.
What is a stolon?
Stolons are similar to runners but grow beneath the ground and can form tubers, like in the case of Irish potatoes.
What are tubers, and what role do they play in plants?
Tubers are thickened stems that store starch, allowing the plant to overwinter, like in potatoes.
What is a bulb, and what are its components?
A bulb is a large bud surrounded by fleshy leaves that store food, with a small stem at the lower end and adventitious roots growing from the bottom.
What are cladophylls, and in which plants are they found?
Cladophylls are flattened stems that resemble leaves, found in plants like butcher’s broom, asparagus, and prickly pear cacti.
What is the function of xylem in vascular plants?
Xylem transports water and nutrients from the roots to the rest of the plant, moving water vertically through vessels and laterally through pits.
What is the function of phloem in vascular plants?
Phloem transports food, mainly sucrose, in various directions depending on the plant’s needs, from sources (where food is produced or stored) to sinks (where food is used or stored).
What are annual rings in woody stems?
Annual rings consist of spring wood (larger vessel elements) and summer wood (smaller vessels), representing one year of growth in the xylem.
What is the vascular cambium, and what tissues does it produce?
The vascular cambium is a meristematic layer that produces secondary xylem (wood) and secondary phloem, increasing the girth of the stem.
What are monocotyledonous stems, and how are they structured?
Monocot stems have vascular bundles scattered throughout the stem, with xylem closer to the center and phloem nearer to the surface.
What are the main tissue patterns found in stems?
The primary tissue patterns are prostele (solid core), siphonostele (tubular with pith), and eustele (discrete vascular bundles).
What are the main features of a corm, and how does it differ from a bulb?
A corm is mainly stem tissue covered with papery leaves and stores food, whereas a bulb has fleshy leaves that store food and a small stem at the base.
What is the function of tendrils in specialized stems?
Tendrils, such as those in Boston ivy, help the plant climb by attaching to surfaces with adhesive disks or adventitious roots.
How do thorns function in plants, and what kind of stem modification are they?
Thorns are modified stems that protect plants from herbivores by providing a physical defense.
What are cladophylls, and how do they differ from true leaves?
Cladophylls are flattened stems that perform photosynthesis and resemble leaves, but they bear small scale-like leaves at their nodes.
What role do stolons play in plant reproduction?
Stolons, which grow underground, produce new plants at their tips or along their length, as seen in Irish potato plants.
How are specialized stems adapted for food storage?
Specialized stems like tubers, bulbs, and corms are adapted to store starch and other nutrients, allowing plants to survive unfavorable seasons.
