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INTRODUCTION, TO PARTS OF A PLANT, , INTRODUCTION, , Either single or various parts of the same plant can be use, hence it becomes necessary to know various parts of a plant cer ‘ ; Soak, may either constitute cellular or acellular organ of the plant. Cellular rugs rs r y, known as organised crude drugs whereas acellular drugs as unorganised crude-drugs., , Before dealing with the drugs in details, one should know how to distinguish clearly, between organised (cellular) and unorganised (acellular) crude drugs., , Table 4.1 ; Difference between Organised and Unorganised Drugs, , used as source of drug and, tifically. Natural drugs, , , , , , , , Organised crude drugs - Unorganised crude drugs, 1. As the term indicates these are 'organs'} 1. These are derived from parts of plant or, of plants or animals and are made up of animal by some process of extraction, cells or definite structure. These drugs and followed by purification, _ if, are named as flowers, seeds, fruits, . necessary, e.g. juices, extracts, resins, insects etc. etc., 2. These.are solid in nature. 2. These are solid, semisolid or liquids in, , nature, e.g., oils and balsams., , , , Botanical or zoological. terminology |3. Such terminology is inadequate to, can be used to describe these drugs. describe them, but one has to look for, their physical characters, such as the, solubility in various solvents, density,, optical rotation, — refractive index,, whichever is applicable., , , , , , , , , , contd..., , (44)

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Introduction to Parts, 2 of, A Text Book of Pharmacognosy 4 a Py, 4. Chemical tests and physical standarg), , are confirmatory tests for identificatg, of these drugs. |, , Examples Aloe, agar, colophony, opium, castor oil, bees-wax, pepsin et, , clers are one of the, , 4. Microscopic chara e of |, for the identification, , important criteria, of organised drugs., Digitalis, cinchona, clove,, ephedra, cochineal etc., , ORGANISED DRUGS, , Examples :, fennel, jalap,, , , , , , , , 1. LEAVES, , There are several leaves,, thin, green appendages to the stem,, structures., , which find use in the practice of pharmacy. Leaves are fly, , containing, supporting and conducting strands in the, , the word leaf includes leaf, compound leaf and_leafle, leaves, many a time, include the flowering top, f active constituents is specified. The bas, , In pharmacognosy,, Depending upon their biological sources,, In certain cases, the minimum percentage 0, , difference between the leaf and the leaflet is as follows., , le Table 4.2 : Difference between Leaf and, , Leaflet, , , , Leaf, , Leaflet, , , , In case of leaves, bud or branch is, present in the axil., , It is abse:~- 1 leaflets., , , , , , , , , , the bases, e.g. digitalis, belladonna,, vasaka, , , , 2. Leaves are arranged spirally and they Leaflets are arranged in pairs:, are solitary in nature. ,, Leaves lie in different planes. Leaflets lie in the same plane., 4. Leaves are generally symmetrical at] _ Leaflets are asymmetrical at the bases,, , e.g. senna, neem, rose.

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Preparation of the Leaves for the Market:, , The leaves atte drying are graded as broken and entire leaves or depending upon their, colour. Tossing and sieving are also done in many of the cases. The packaging of leaves is, likely to affect quality of the drug. In order to maintain the quality and potency of leaves,, , wherever necessary, leaves should be packed in air-tight containers protected from light, and moisture., , Diagnostic Characters of Leaves :3 py CS~ |g, , Apart from shape, size and colour, leaves are-Characterized by several microscopic, , structures which help in their proper identification. Following are few diagnostic, characters of common occurrence. ., , [A] Stomata:( |, , Epidermis of leaf shows different characteristics, e.g. cutical stomata, trichomes, waterpore, cell inclusions, etc. A Stoma is a minute epidermal opening with following, characteristics., , (i) Acentral pore., , (ii) Two kidney shaped similar cells containing chloroplasts known as guard cells and, , varying number of subsidiary (epidermal) cells covering the guard cells., , Stomata perform two functions in the plant body. The primary and most important, function of stomata is gaseous exchange and the secondary function is transpiration., , It is not essential that each plant must have stomata. The leaves of bryophytes and, submerged leaves of aquatic parts do not contain stomata. Generally, stomata are present, in green parts of the plant (mostly leaves), but absent in rcots. Apart from the leaves, they, are also present in the stems (ephedra), flowers (clove), and fruits (fennel). However, it is, generally observed that stomata are abundantly present in dicot leaves. In some cases,, they are present on the upper surface of leaves, while in others on lower surface only, (coca and cherry). In some, the stomata are present on both surfaces of the leaves (senna,, belladonna, datura etc.). The distribution of stomata between upper and lower epidermis, in dicot leaves shows great variation., state of Stomata : Depending upon the type of the guard cells and arrangement of, , iary cells, stomata are divided into four types., , Moss type., Gymnospermous type., Gramineous type., , ly, 2., 3., 4. Dicotyledonous type.

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ook of Pharmacognosy, mem, _Introduction to Parts of a Plant, , a p SANGGTA: Maeancis, , Indian Pharmacopoeia recognizes one more lype of stornata known as Actinocytic, stomata., , 5 Actinocytic or radiate-celled stomata : Th :, , 5. “ 7 ata : The two guard cells are surrou, circle of radiating subsidiary cells, < papel, [B] Leaf Constants > :x.)) GS-15 ( aN, , Vein-islet ca is defined as the number of vein-islets per sq. mm of the leaf surface, midway between the midrib and the margin. Levin, in 1929, determined vein-islet, , numbers of several dicot leaves., , Vein-termination number is defined as the number of veinlet terminations per sq. mm., of the leaf surface midway between midrib and margin. Stomatal number is the average, number of stomata per sq. mm of epidermis of the leaf. Stomatal index is the percentage, which the number of stomata form to the total number of epidermal cells, each stoma, being counted as one cell., , Palisade ratio is defined as the average number of palisade cells beneath each °, epidermal cell. It can be determined with powdered drugs. - ~, , The technique of determination of leaf constants can be used for microscopic, evaluation of several leaf drugs such as senna, datura, digitalis, buchu, coca, belladonna, , etc., [C]_Water Pores : QD, , Water pores and stomata resemble each other to some extent in structure and, functions. Water pores are immovable unlike stomata and they are present on the teeth of, , the margin., , TN), [D] Trichomes C4) ., , They are another important diagnostic character helpful in the identification of drugs:, and detection of adulterants. Trichomes are the tubular elongated or glandular outgrowth, of the epidermal cell. Trichomes are also called as plant hairs. Trichomes consist of two, parts viz., root (in the epidermis) and body (outside the epidermis). Trichomes are present, in most of the parts of the plant such as leaves (senna and digitalis), seeds (nux-vomica, and strophanthus), fruits (Helicteris isora and Ladies finger) etc. Trichomes are as such, functionless, but sometimes, perform secretary function. The trichomes excrete water and, at times, volatile oil as in case of peppermint. Trichomes are present in most of the aerial, Parts of the plant, but are absent on roots. They are absent in coca, sevin and hemlock and, rarely present in buchu and henna. Depending upon the structure and the number of cells, Present in trichomes, they are classified as given below :, , 1. - Covering trichomes or non-glandular trichomes or clothing trichomes;, 2, , 3, , Glandular trichomes;, Hydathodes or special type of trichomes: