Podcast
Questions and Answers
ما هو تعريف المُصطلح النبات العشبي؟
ما هو تعريف المُصطلح النبات العشبي؟
النبات العشبي هو نبات ذو ساق ناعمة يمكن كسرها بسهولة، وله سطح أملس أو شعري.
ما هو تعريف العُشب من وجهة نظر علم النبات؟
ما هو تعريف العُشب من وجهة نظر علم النبات؟
العشب هو نبات ذو ساق لا تصبح خشبية ولا دائمة، بل تموت بعد الإثمار.
ما هي أنواع العُشب؟
ما هي أنواع العُشب؟
أنواع العُشب هي سنوية، ثنائية الحول ، ودائمة.
ما هي الأدوية التي يُستخرج منها العُشب؟
ما هي الأدوية التي يُستخرج منها العُشب؟
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ما المقصود بـ الساق الأرضية?
ما المقصود بـ الساق الأرضية?
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ما هي وظيفة ساق النبات؟
ما هي وظيفة ساق النبات؟
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ما هو نوع العُشب الذي ينمو لمدة سنة واحدة قبل إنتاج البذور ثم يموت؟
ما هو نوع العُشب الذي ينمو لمدة سنة واحدة قبل إنتاج البذور ثم يموت؟
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ما هو نوع العُشب الذي ينمو لمدة عامين قبل إنتاج البذور ثم يموت؟
ما هو نوع العُشب الذي ينمو لمدة عامين قبل إنتاج البذور ثم يموت؟
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ما هو نوع العُشب الذي ينمو لمدة سنتين أو أكثر ويكون له جذور دائمة؟
ما هو نوع العُشب الذي ينمو لمدة سنتين أو أكثر ويكون له جذور دائمة؟
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ما المقصود بـ العُقد في ساق النبات؟
ما المقصود بـ العُقد في ساق النبات؟
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ما هي أنواع تركيب ساق النبات؟
ما هي أنواع تركيب ساق النبات؟
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ما المقصود بـ الزوائد المتسلقة?
ما المقصود بـ الزوائد المتسلقة?
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ما هو تعريف اللولب في ساق النبات؟
ما هو تعريف اللولب في ساق النبات؟
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ما المقصود بـ التصنيف الورقي في ساق النبات؟
ما المقصود بـ التصنيف الورقي في ساق النبات؟
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ما هي أنواع التصنيف الورقي؟
ما هي أنواع التصنيف الورقي؟
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ما المقصود بـ اللب في ساق النبات؟
ما المقصود بـ اللب في ساق النبات؟
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ما هي خصائص الطبقة الخارجية لساق نبات ذوات الفلقتين؟
ما هي خصائص الطبقة الخارجية لساق نبات ذوات الفلقتين؟
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ما هي خصائص النسيج الأساسي لساق نبات ذوات الفلقتين؟
ما هي خصائص النسيج الأساسي لساق نبات ذوات الفلقتين؟
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Study Notes
Pharmacognosy-2
- This lecture is about Pharmacognosy-2.
- The lecturer is Ahmed Elbermawi, PhD, a Lecturer of Pharmacognosy.
- Herbs are plants whose stems don't become woody permanently, but die after fruiting.
- Pharmacognosy is a drug composed of tender parts of plant axis, leaves, flowers, and fruits from annual, biennial, or perennial plants.
- Herbs consist of flowering tops of flowering plants (e.g., Cannabis) and whole aerial parts of plants (e.g., Lobelia).
Types of Herb
- Annual: Live for one season before seed production and then die.
- Biennial: Live for two seasons before seed production and then die (e.g., Digitalis).
- Perennial: Live for more than two years, have perennial rootstocks, and throw up aerial shoots annually (e.g., Belladonna).
Definition of a Stem
- A stem is part of the plant axis that bears leaves or modifications of leaves.
- Aerial stems grow above ground.
- Subterranean stems grow below ground.
Functions of Aerial Stem
- Conducting water and mineral nutrients from the root to the leaves.
- Conducting food from the leaves to the root.
- When leaves are reduced, the stem serves for assimilation.
Morphological Characters
- Shape
- Color
- Type (Herbaceous, Succulent)
- Branching
- Surface
- Fracture
- Insertion of leaves
- Phyllotaxis
- Pith
Types
- Herbaceous: Soft stem, easily broken, with smooth or hairy surfaces.
- Succulent: Thick, fleshy stems.
Types of Stem Growth
- Creeper: Spread horizontally rather than vertically, producing new plants along the way.
- Runner: Long, slender, trailing shoots running on the surface, giving roots at nodes, with small brown scale leaves with buds in their axils.
- Sucker: Underground runner, later becoming aerial.
- Climber: Weak stems that attach themselves to support using tendrils or hooks.
- Twining: Grows in a spiral fashion around a suitable support.
Insertion of Leaves
- Cauline: Arise from the aerial stem.
- Radical: Arise from the crown of the root.
Phyllotaxis
- Alternate or spiral: Leaves occur singly at a node.
- Opposite: Occur in pairs at a node.
- Opposite decussate: Opposite, but each pair alternates at right angles to the other one.
- Whorled: Several leaves occur at a node.
Microscopical Characters - Dicot. Stem
- Cambium: Arranged in a single ring around the central region called pith.
- M.R.: A number of parenchymal strands between vascular bundles (V.B.) from the pith to the cortex.
- Ground tissues: Composed of cortex, pith, and medullary rays (M.R.).
Microscopical Characters - Monocot Stem
- Large number of closed collateral vascular bundles scattered irregularly throughout the ground tissues.
- Smaller and more crowded near the periphery of the stem than in the center.
- Pith, medullary rays (M.R.), limit of cortex, endodermis, and pericycle are indistinguishable.
Herbs of Medicinal Uses
- Various examples/types of medicinal herbs are mentioned.
Lobelia Herb (Asthma Weed, Indian, or American Lobelia)
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Dried aerial parts of Lobelia inflata L.
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Family: Companulaceae
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Macroscopical characters include stem (green to yellowish green color with large purple patches), leaves (alternate, stiff hairs), flowers (two-lipped tubular flower, shortly pedicellate, arranged in long raceme inflorescence), pale blue calyx, long with 5 linear teeth.
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Corolla: tubular, bilabiate (two-lipped).
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Stamens: 5 stamens united by their anthers (syngenesious) forming a tube enclosing the bifid stigma (two sections).
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Ovary: bilocular (two chambers) and bicarpellary.
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Fruit: Inflated capsule, dehiscing by 2 pores at top, ovoid, membranous pericarp
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Bilocular
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Numerous seeds arranged on an axial placenta
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Seeds: Minute, oblong, polygonal reticulation.
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Leaf: Dorsiventral with a single palisade layer, numerous small rod-shaped crystals of fat, midrib with central vascular bundle (V.B.), laticiferous vessels in phloem.
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Stem: Beaded, straight-walled cells with striated cuticle, few anomocytic stomata, numerous trichomes.
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Cortex: Chlorenchyma (collenchyma present), endodermis with distinct lignified Casparian strips.
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Stellar Tissues: Includes pericycle (parenchymatous with patches of pericyclic fibers), continuous ring of vascular bundles (V.B.), phloem, and pith (central large pith of lignified thin-walled parenchyma)
Powder
- Properties including Color, Odor, and Taste describe characteristics.
- Upper and Lower epidermis are included in the powder section, along with stomata and trichomes (including details of the structure of trichomes in the lower epidermis)
Active Constituents
- Lobeline (major alkaloid), lobelidine, lobelanine, lobelanidine, isolobelanine.
- Other constituents like inflatin, lobelic acid, wax, and resin.
Chemical Test
- Alkaloidal extract + few drops of H₂SO₄ + one drop of formalin produces a red color.
Uses
- Smoking deterrent (lozenges).
- Bronchial asthma (relaxes bronchial muscles).
- Respiratory stimulant (dyspnea of chronic bronchitis).
- Expectorant (for loosening mucus in lungs).
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