Introduction to Pharmacognosy: Botanical Description of Plant Crude Drugs

Comprehensive practice flashcards defining essential botanical and pharmacognostical terms for leaves, flowers, fruits, seeds, barks, woods, and subterranean structures.

Angle of Divergence

The regular measurable angle between subsequent leaves arranged along a shoot in a screw pattern, commonly measuring $180^\circ$, $120^\circ$, $144^\circ$, or $135^\circ$.

Structure of a Typical Leaf

A vegetative organ organized into a leaf-base attached to the stem, a petiole (leaf stalk), and an expanded green leaf-blade (lamina) traversed centrally by a mid-rib.

Simple Leaf

A leaf consisting of a single lamina that is not completely divided into distinct leaflets, such as in Stramonium, pawpaw, and cassava.

Compound Leaf

A leaf whose lamina is completely divided into individual leaflets that lack axillary buds in their axils and typically lie in the same plane.

Pinnate Compound Leaf

A compound leaf wherein leaflets are borne along an axis known as a rachis; sub-classified as unipinnate (paripinnate or imparipinnate), bipinnate, tripinnate, or decompound.

Paripinnate

A unipinnate compound leaf possessing an even number of leaflets, as seen in tamarind and gul mohor.

Imparipinnate

A unipinnate compound leaf possessing an odd number of leaflets terminated by a single apical leaflet, as found in rose and margosa.

Palmate Compound Leaf

A compound leaf whose leaflets are articulated directly from the apex of the petiole; sub-divided into unifoliate, trifoliate, and multifoliate types.

Reticulate Venation

A pattern of venation characteristic of dicotyledonous leaves where veins and veinlets form an interconnected network; divided into unicostate and multicostate types.

Parallel Venation

A venation pattern characteristic of monocotyledons in which veins run alongside each other without forming a reticulate meshwork.

Phyllotaxy

The mode of arrangement of leaves along a stem or branch, comprising alternate (spiral), opposite (decussate and superposed), whorled, and leaf mosaic types.

Opposite Decussate

An arrangement where two opposite leaves at one node stand at right angles ($90^\circ$) to the pairs of leaves situated directly above and below.

Leaf Mosaic

A leaf arrangement pattern in which older leaves possess longer petioles and younger leaves have shorter petioles to avoid overlapping and maximize sunlight exposure, as seen in Oxalis.

Peltate Leaf

A shield-shaped leaf lamina where the petiole is attached to the lower surface near the center rather than to the basal margin.

Leaf Apex Types

Morphological variations of the leaf tip including obtuse (rounded), acute (sharp angle), acuminate (slender tail), cuspidate (rigid point), truncate (abruptly cut), emarginate (deeply notched), and cirrhose (tendril-like).

Leaf Base Shapes

The morphology of the basal part of the lamina, categorized as symmetrical (equal), asymmetrical (unequal), decurrent, or cordate.

Mesophyll

The ground tissue located between the upper and lower leaf epidermises, differentiated into upper palisade parenchyma and lower spongy parenchyma.

Diacytic Stoma

A caryophyllaceous or Labiatae type stoma enclosed by two subsidiary cells whose shared contact wall lies at right angles ($90^\circ$) to the long axis of the stoma.

Anisocytic Stoma

A cruciferous or Solanaceous type stoma surrounded by three subsidiary cells, one of which is markedly smaller than the other two.

Anomocytic Stoma

A ranunculaceous type stoma surrounded by a variable number of epidermal cells that do not differ in shape or size from ordinary epidermal cells.

Paracytic Stoma

A rubiaceous type stoma accompanied by two subsidiary cells whose longitudinal axes lie parallel to the stoma aperture.

Actinocytic Stoma

A radiate-celled stoma surrounded by a definite circular ring of radially elongated subsidiary cells, characteristic of Uva ursi.

Trichomes

Elongated epidermal outgrowths consisting of a basal foot embedded in the epidermis and an external projecting body; classified broadly into covering (non-glandular) and glandular hairs.

Stramonium

The dried leaves and flowering tops of Datura stramonium Linn. (Solanaceae), containing not less than $0.25\%$ alkaloids calculated as hyoscyamine, displaying anisocytic stomata and uniseriate conical covering trichomes.

Senna

The dried leaflets of Cassia angustifolia or Cassia acutifolia (Caesalpiniaceae), containing anthraquinone glycosides sennoside A and sennoside B ($\ge 2.0\%$ sennoside B), paracytic stomata, and warty unicellular trichomes.

Digitalis

The dried leaves of Digitalis purpurea or Digitalis lanata (Scrophulariaceae), containing cardiac glycosides (digoxin, digitoxin) that increase cardiac contractility; characterized by anomocytic stomata and absence of calcium oxalate crystals.

Cannabis

Dried leaves and flowering tops of Cannabis sativa (Cannabaceae), containing cannabinoids such as delta-1-tetrahydrocannabinol ($\text{THC}$) and trichomes bearing cystoliths of calcium carbonate.

Flower Structure

A sexual reproductive shoot consisting of four floral whorls: calyx (sepals), corolla (petals), androecium (stamens), and gynoecium/pistil (carpels) inserted on a receptacle (thalamus).

Perianth

The non-reproductive collective floral envelope used when the calyx and corolla are morphologically undifferentiated, composed of individual units termed tepals.

Pyrethrum Flower

The dried flower heads of Chrysanthemum cinerariaefolium or Chrysanthemum coccineum (Asteraceae), containing at least $0.7\%$ total pyrethrins (pyrethrins I and II, cinerins, jasmolines) used as contact insecticide poisons.

Clove

The dried flower buds of Eugenia caryophyllus Bull. (Myrtaceae), yielding not less than $15\%\,\text{v/w}$ volatile oil rich in eugenol and used as a dental analgesic and antiseptic.

Pericarp

The wall of a ripened fruit derived from the ovary wall, typically differentiated into epicarp (outer skin), mesocarp (middle fleshy or fibrous layer), and endocarp (inner layer).

Pseudocarp (False Fruit)

A fruit formed from the ovary along with accessory floral parts like the thalamus or calyx, such as cashew nut, apple, and strawberry.

Follicle

A dry dehiscent monocarpellary fruit containing one or many seeds that dehisces longitudinally along a single suture, as in Calotropis.

Legume

A dry dehiscent fruit developing from a single carpel that splits open along both dorsal and ventral sutures, as in Acacia and Pisum sativum.

Siliqua

A long, slender, multi-seeded dry dehiscent fruit derived from a bicarpellary ovary that splits along two long sutures from base to apex, as in cabbage and radish.

Capsule

A dry dehiscent multi-seeded fruit formed from a syncarpous, unilocular or multilocular ovary that splits open by various dehiscence mechanisms to release seeds.

Achene

A small, dry, single-chambered, single-seeded indehiscent fruit whose seed coat remains free from the thin pericarp, as in sunflower.

Caryopsis

A simple dry indehiscent one-seeded fruit where the seed coat is intimately fused with the pericarp, characteristic of the grass family (Poaceae) such as sweet corn and wheat.

Samara

A dry indehiscent winged fruit with one or two seeds where part of the fruit wall forms flattened wing-like outgrowths for wind dispersal, as in Dioscorea.

Drupe

A fleshy fruit typically formed from a single carpel, characterized by a thin epicarp, fleshy mesocarp, and a stony, lignified endocarp enclosing a single seed.

Pome

A false fleshy fruit derived from an inferior compound ovary enclosed by a fleshy, enlarged hypanthium/thalamus, as found in apples and pears.

Hesperidium

A specialized many-chambered berry possessing a tough, glandular, aromatic leathery rind (peel) and internal pulp filled with juice-sacs, typical of Citrus fruits.

Sorosis

A multiple or composite fruit developed from a spiked inflorescence whose constituent flowers fuse together via their fleshy sepals into a compact mass, as in pineapple.

Syconus

A composite fruit formed from an entire inflorescence within an enlarged, fleshy, hollow, flask-shaped receptacle enclosing minute unisexual flowers, as in Ficus (fig).

Capsicum

The dried ripe fruits of Capsicum annuum Linn. (Solanaceae), containing $0.5\%$ to $0.9\%$ pungent crystalline capsaicin and used internally as a stomachic and externally as a counter-irritant.

Fennel Fruit

The dried ripe cremocarp of Foeniculum vulgare Miller (Umbelliferae), featuring five primary ribs, anomocytic stomata, and containing $3\%$ to $7\%$ volatile oil with anethole ($50\%$) and fenchone ($20\%$).

Cardamom Fruit

The dried ripe 3-sided capsules of Elettaria cardamomum Maton (Zingiberaceae), containing volatile oil with cineol as the active constituent, used as a carminative and flavorant.

Endospermic (Albuminous) Seed

A seed in which the developing embryo does not fully absorb the nutritive endosperm tissue prior to dormancy, as found in castor bean, nux vomica, and strophanthus.

Non-Endospermic (Exalbuminous) Seed

A seed where the embryo completely consumes the endosperm during maturation, storing reserve food directly in fleshy cotyledons, as in sunflower and soybean.

Perispermic Seed

A seed containing persistent nutritive tissue derived from the maternal nucellus (perisperm) alongside the embryo and endosperm, seen in pepper, cardamom, and nutmeg.

Nutmeg

The kernel of the dried ripe seed of Myristica fragrans Houtten. (Myristicaceae), containing $5\%$ to $15\%$ volatile oil rich in myristicin and elemicin.

Castor Oil

The fixed oil obtained by cold expression of Ricinus communis (Euphorbiaceae) seeds; contains triricinolein, acting as a stimulating purgative and emollient.

Bark (Botanical)

All tissues lying external to the vascular cambium in the stem or root of a woody plant, including periderm (cork, phellogen, phelloderm), cortex, pericycle, and phloem.

Coppicing Method

A harvesting method where plants are grown to a specific age and cut near ground level; new shoots regenerate from the remaining stump and are periodically harvested for bark.

Double Quill

A dried bark configuration where both lateral edges curve inward towards each other, as observed in Cinnamon and Cassia barks.

Compound Quill

A commercial bark preparation where smaller peeled quills of bark are nested tightly inside larger diameter quills to optimize packing and shipping space.

Cinchona Bark

Dried bark of Cinchona species (Rubiaceae) containing quinoline alkaloids (quinine, quinidine, cinchonine, cinchonidine), displaying a short fibrous fracture and used as a febrifuge and antimalarial.

Cinnamon Bark

The dried inner bark of coppiced shoots of Cinnamomum zeylanicum Nees (Lauraceae), characterized by compound quills lacking cork and cortex, containing volatile oil, cinnamaldehyde, and eugenol.

Heartwood

The central, non-conducting, mechanically supportive dead xylem cylinder of woody stems impregnated with tannins, resins, and gums, and obstructed by tyloses.

Sapwood

The peripheral, physiologically active, lighter-colored secondary xylem zone that conducts sap (water and minerals) from roots up to leaves.

Quassia Wood

The dried stem wood of Picraena excelsa (Simarubaceae), containing intensely bitter amaroids (quassin, isoquassin, neoquassin) devoid of tannic acid, used as a bitter stomachic and anthelminthic enema.

Sandalwood

The dense heartwood of Santalum album Linn. (Santalaceae), yielding $2\%$ to $5\%$ volatile oil composed of $90\%$ to $97\%$ sesquiterpene alcohols (santalol) used as a urinary disinfectant and in perfumery.

Rhizome

A thickened horizontal or oblique underground stem possessing distinct nodes, internodes, scale leaves with axillary buds, and adventitious roots, as in Ginger and Turmeric.

Corm

A shortened, solid, fleshy vertical subterranean stem serving as an organ of vegetative storage and perennation, bearing scale leaves and buds, as in Colchicum autumnale.

Bulb

A modified underground storage organ consisting of a reduced disc-like stem supporting a apical shoot bud surrounded by concentric layers of fleshy scale leaves, as seen in squill and onion.

Rauwolfia

The dried sub-cylindrical roots of Rauwolfia serpentina Benth (Apocynaceae), containing $1.2\%$ to $1.4\%$ indole alkaloids (reserpine, rescinnamine) used as an antihypertensive and sedative.

Belladonna Root

The dried cylindrical roots and rootstocks of Atropa belladonna Linn. (Solanaceae), rich in tropane alkaloids (hyoscyamine, hyoscine) and sandy microsphenoidal crystals of calcium oxalate.

Ginger

The scraped, peeled, and dried horizontal rhizomes of Zingiber officinale Roscoe (Zingiberaceae), containing gingerol and volatile oils (zingiberene), displaying non-lignified reticulate vessels and mealy fracture.

Turmeric

The boiled and dried primary or secondary rhizomes of Curcuma domestica Val. (Zingiberaceae), characterized by a bright orange-yellow color due to curcumin ($5\%$) and gelatinized starch.

Colchicum Corm

The dried reniform transverse slices of the corm of Colchicum autumnale Linn. (Liliaceae), containing the toxic alkaloid colchicine ($\approx 0.6\%$) used to treat acute gout by halting microtubule spindle formation.