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Questions and Answers
What type of pinnately compound leaf has a rachis with a single leaflet at the end?
What type of pinnately compound leaf has a rachis with a single leaflet at the end?
Which of the following leaf shapes is described as needle-shaped?
Which of the following leaf shapes is described as needle-shaped?
What is the lamina type with a margin that has sharp teeth directed toward the apex called?
What is the lamina type with a margin that has sharp teeth directed toward the apex called?
What type of palmately compound leaf has leaflets arising from multiple points along the petiole?
What type of palmately compound leaf has leaflets arising from multiple points along the petiole?
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Which plant example corresponds with an ovate leaf shape?
Which plant example corresponds with an ovate leaf shape?
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What describes the lamina shape where the widest portion is near the apex?
What describes the lamina shape where the widest portion is near the apex?
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Which margin type of the leaf is characterized by having numerous minute rounded lobes?
Which margin type of the leaf is characterized by having numerous minute rounded lobes?
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Which lamina shape has the highest width at the base and tapers towards the apex?
Which lamina shape has the highest width at the base and tapers towards the apex?
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What term describes leaves that grow in pairs and are inserted at right angles to those above and below?
What term describes leaves that grow in pairs and are inserted at right angles to those above and below?
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Which part of the leaf serves as the attachment to the stem and may develop stipules?
Which part of the leaf serves as the attachment to the stem and may develop stipules?
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What type of leaf has a continuous undivided surface?
What type of leaf has a continuous undivided surface?
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When a leaf blade is completely divided into several separate leaflets, it is referred to as what type of leaf?
When a leaf blade is completely divided into several separate leaflets, it is referred to as what type of leaf?
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Which type of leaf arises with leaves occurring in a circle around the stem?
Which type of leaf arises with leaves occurring in a circle around the stem?
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What is the feature of a petiole that aids in the adjustment of leaf movement towards light?
What is the feature of a petiole that aids in the adjustment of leaf movement towards light?
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Which of the following describes a leaf that does not have a petiole?
Which of the following describes a leaf that does not have a petiole?
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In pinnately lobed leaves, the incision is directed towards which part of the leaf?
In pinnately lobed leaves, the incision is directed towards which part of the leaf?
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What defines an entire leaf margin?
What defines an entire leaf margin?
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Which leaf apex type is characterized by a tip that forms an acute angle?
Which leaf apex type is characterized by a tip that forms an acute angle?
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What is the term for a leaf base that is heart-shaped?
What is the term for a leaf base that is heart-shaped?
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How is parallel venation characterized?
How is parallel venation characterized?
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What differentiates a lobed leaf from a parted leaf?
What differentiates a lobed leaf from a parted leaf?
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What leaf surface characteristics define a hairy leaf?
What leaf surface characteristics define a hairy leaf?
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Which of the following best describes a mucronate leaf apex?
Which of the following best describes a mucronate leaf apex?
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What venation pattern has lateral veins extending regularly from a midrib?
What venation pattern has lateral veins extending regularly from a midrib?
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What is the primary distinction between a leaf and a stem?
What is the primary distinction between a leaf and a stem?
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Which type of leaf is primarily responsible for the storage of reserve food material?
Which type of leaf is primarily responsible for the storage of reserve food material?
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What characterizes foliage leaves?
What characterizes foliage leaves?
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Which of the following is a characteristic of floral leaves?
Which of the following is a characteristic of floral leaves?
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What is phyllotaxis?
What is phyllotaxis?
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What describes opposite superposed leaves?
What describes opposite superposed leaves?
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Which term describes leaves crowded together around the top of the root?
Which term describes leaves crowded together around the top of the root?
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Which structure is specifically a type of modified leaf?
Which structure is specifically a type of modified leaf?
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Study Notes
Medicinal Plants 2024/2025 Fall Semester
- Course offered at El Saleheya El Gadida University, Faculty of Pharmacy
- Focuses on the study of medicinal plants specifically during the fall semester of 2024/2025
Lecture 7: The Leaf
- Definition: A lateral outgrowth on the stem that differs in structure and organization from the stem.
- It lacks nodes and internodes but includes an axillary bud.
- Composition: A complete leaf is comprised of the leaf base, petiole (leaf stalk), and lamina (blade).
Types of Leaves
- Cotyledons (Seed leaves): Used for storing reserve food materials (proteins). Monocots have one; dicots have two; gymnosperms often have more.
- Prophylls: Often the first leaves, differing in form and structure compared to foliage leaves.
- Foliage leaves: Ordinary green leaves carrying typical leaf functions and containing chlorophyll.
Bracts
- Leaves that bear flowers or flower groups in their axils.
Scale Leaves
- Thin, membranous leaves lacking chlorophyll, commonly found on subterranean and some aerial stems.
Floral Leaves
- Include sepals, petals, stamens, and carpels.
Modified Leaves
- Leaves that have been altered to perform specific functions:
- Tendrils: Support structures (e.g., pea plants)
- Spines: Protection (e.g., cacti)
- Insect-catching traps: Specialized structures (e.g., Drosera)
- Succulents: Water storage (e.g., Zygophyllum)
Morphology of Leaf
- Texture: Brittle, coriaceous, papery, fleshy, etc.
- Odor: Aromatic or odorless.
- Taste: Bitter, sweet, mucilaginous, etc.
- Insertion: Cauline (leaves on a long stem), Radical (leaves clustered at the stem's base near the soil).
Phyllotaxis
- Leaf arrangement on the stem:
- Alternate/Spiral: Leaves inserted singly at nodes.
- Opposite: Leaves in pairs at each node; superposed (pairs are parallel to other pairs), or decussate (pairs are perpendicular to other pairs).
- Whorled/Verticillate: Three or more leaves originate at a node, forming a circular pattern around the stem.
Leaf Structure
-
Petiole: Leaf stalk, attaching the blade to the stem.
- Petiolate: A leaf having a petiole.
- Sessile: A leaf lacking a petiole.
- Stipules: Lateral outgrowths from the leaf base that protect the bud (Stipulate) or absent (Exstipulate)
- Lamina: Leaf blade (flat and widest portion of leaf).
Lamina (Leaf-blade)
-
Simple leaves:
- Entire: Continuous undivided surface.
-
Lobed: Cut into lobes connected by an undivided portion.
- Pinnately lobed: Incisions towards leaf midrib.
- Palmately lobed: Incisions towards the petiole
-
Compound leaves:
- Consist of leaflets arranged on a central axis (rachis) instead of a single blade.
-
Pinnately compound: Leaflets arranged along the rachis, can be:
- Even Pinnate: two leaflets at the end of the rachis
- Odd Pinnate: single leaflet at the end of the rachis
- Palmately compound: Leaflets originate from a common point on the petiole.
Venation of the Lamina
- Parallel: Veins run parallel to each other.
-
Reticulate: Veins branch off into smaller veins
- Pinnately reticulate: From a main vein to the margin, in a regular pattern.
- Palmately reticulate: Several veins from the base to the apex.
Margin of Lamina
- Entire: Smooth edge.
- Toothed/Serrated: Tooth-like projections.
- Lobed: Indention less than half way to midrib.
- Parted: Indention longer than half way to midrib.
Apex of the Lamina
- Acute: Angle at tip.
- Acuminate: Longer, tapered point.
- Mucronate: Sharp point.
- Emarginate: Acute notch at tip
Base of the Lamina
- Symmetrical: Equal on both sides.
- Asymmetrical: Unequal on both sides.
- Decurrent: Continuous downward as wings along the petiole.
- Cordate: Heart-shaped.
Surface of the Lamina
- Smooth: Free from hairs.
- Glabrous: Free from hairs.
- Hairy: Covered with hairs.
- Papillosed: Small, nipple-shaped protuberances.
- Pubescent: Covered with soft, short hairs.
- Punctate: Marked by dots or pits (often oil glands).
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Description
This quiz covers the essential concepts of leaves, including their definition, composition, and various types. Students will explore cotyledons, prophylls, foliage leaves, bracts, and scale leaves in the context of medicinal plants. Prepare to test your understanding of leaf structures and functions!
