Anatomico-Physiological Classification of Plant Tissue Systems

The below mentioned article provides an overview on the anatomico-physiological classification of plant tissue systems.

Haberlandt proposed the ‘anatomico-physiological’ classifica­tion in his classical book ‘Physiological Plant Anatomy’.

In his classification, function has been taken as the sole criterion while the origin, nature of cells, their topography and other characters were thoroughly ignored. He recognised a few systems like dermal system, absorbing system, and so on.

In spite of all thoroughness and advantages, this system has been confusing, mainly due to utter disregard of the origin of the tissues. Epidermis and cork cells have different origin, but they have been put in the dermal system because of the same protective function.

The guard cells of the stomata and the root hairs originate from protoderm cells; here guard cells have been put in the ventilating system and root hairs in the absorbing system.

To Haberlandt ‘homologies of the tissues were of no interest’, his concern was ‘solely with analogy’. He put tissues into twelve systems, an outline of which is being given.

I. Meristematic tissues included primordial meristem-marginal and apical cells, growth by apical cells and growth by apical initials, primary meristem and secondary meris­tem.

II. The dermal system consisted of epidermis including its nature, wall characters and contents, the multiple epidermis; the epidermal appendages; the secondary meristem phellogen and secondary protective tissues cork and bark. The epidermal openings were excluded.

III. The mechanical system considered the bast fibres, wood fibres, collenchyma, scleren­chyma cells with sclereids; strength and elasticity of mechanical cells; the principles govern­ing the distribution of mechanical tissues in plants and the influence of external factors on the development of the mechanical system (Ref. Chapter XX).

IV. The absorbing system included root hairs, rhizoids, velamen, the absorbing tissue of aerial roots; and water-absorbing hairs of foliage leaves, as regards absorption of in­organic compounds; and systems of absorbing organic food materials among seedlings, saprophytes, parasites and carnivorous plants.

V. The photosynthetic system included chloroplasts, chlorophyll containing par­enchyma—palisade and spongy cells of leaves, and influence of light upon the distribution and organisation of the photosynthetic system.

VI. The vascular or conducting system consisted of the vascular bundles, tracheary and sieve elements, xylem parenchyma, and phloem parenchyma; laticiferous tissues; and the structure of the vascular bundles.

VII. The storage system consisting of water tissues, storage tissues of seeds, tubers and bulbs.

VIII. The aerating or ventilating system was concerned with intercellular spaces, stomata and lenticels; and pneumatophores of breathing roots.

IX. The secretory and excretory systems included hydathodes, digestive glands, nectaries, oil-, resin-, mucilage- and gum-secreting glands.

X. The motor system considered the flying hairs and tissues, hygroscopic tissues, vital motor tissues, etc.

XI. The sensory system covered papillae, hairs, bristles, statolith organs, tactile bristles of carnivorous plants.

XII. The stimulus-transmitting system considered the protoplasmic connections, stimulus-transmitting tissue of Mimosa pudica.