Stems connect a plant’s roots to its leaves and provide support for leaves, flowers, and buds. This lesson explores the stem’s external features and the tissues that carry out its important functions.
Stems are part of the plant’s shoot system. They vary greatly in length and thickness, and may be soft and herbaceous or woody. Most stems grow above ground, but some, such as potato stems, grow underground. Stems can be unbranched or highly branched.
All flashcards
What are nodes and internodes?
Nodes are points where leaves, flowers, or aerial roots attach to a stem. Internodes are the stem regions between adjacent nodes.
What are the roles of parenchyma cells?
Parenchyma cells carry out metabolic functions such as photosynthesis, help repair wounds, and may store starch.
How do collenchyma and sclerenchyma differ?
Collenchyma cells are living and provide flexible support. Many sclerenchyma cells are dead at maturity and have strong, lignin-rich secondary walls.
What do xylem and phloem transport?
Xylem conducts water, while phloem transports organic substances, including sugars and amino acids.
What are pith and cortex in a stem?
Pith is ground tissue inside the vascular tissue. Cortex is ground tissue between the vascular tissue and epidermis.
Quiz questions
What is apical dominance?Answer: Suppression of axillary bud growth by the apical bud.
In a stem cross section, what does having vascular bundles scattered through the ground tissue indicate?Answer: The stem has a monocot bundle arrangement.
What is the role of companion cells in phloem?Answer: They provide metabolic support to sieve-tube cells.
What function do lenticels perform in some periderm?Answer: They allow gas exchange with living internal tissues.
What are plant thorns, as described in stem modifications?Answer: Sharp modified branches that help protect the plant.
Based on Biology 2e by Mary Ann Clark, Matthew Douglas, Jung Choi (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.