Question

Complex/ special tissue is
(a) Sclereid
(b) Sclerenchyma
(c) Collenchyma
(d) Secretory tissue

Answer 1

Hint: These cells are cells that can be elongated so called sacs or tubes. These cells are idioblasts dispersed among less specialized cells. They are classified based on their contents, but many cells contain mixtures of substances. Such as rutaceae, others with seminiferous cells or mucilaginous cells

Complete step by step answer:
- Secretory tissues in plants are of two types:
Glandular Tissues: Glands and Trichomes
Laticiferous tissues: Ducts and Laticifers
- The secreted substances may be:
Excess of ions removed in a form of certain salts,
Excess of products such as sugars or cell wall substances
Products that will not be used physiologically as alkaloids, tannins, terpenes, resins, crystals
Some secretory substances are waste products.
- Glandular trichomes are specialized hairs found on the surface of a plant's leaf.
- Trichomes have unicellular or multicellular heads composed of cells producing the secretion found on a stalk of non glandular cells. - Oil secreting trichomes, oil could be stored in vesicles in cytoplasm or stored in plastids.
Example:
- Oil secreting trichomes: mint, geranium, lavender
- Stinging hairs in Urtica: nettle plant
So, the correct answer is, ‘secretory tissue.’

Additional information:
Sclerenchyma
- The cells are long, narrow, thick and lignified, which are usually pointed at both ends.
- Nucleus is absent therefore the tissue is made up of dead cells.
- They have simple, oblique pits in the walls.
- The middle lamella i.e. the wall between adjacent cells is conspicuous.
- Found abundantly in the stems of plants like hemp, jute and coconut.
- It is present in stems, around vascular plants , in the leaves, hard covering of seeds and nuts.
Sclereids
- Sclereids tissue also known as stone cells or sclerotic cells.
- Found most common in fruits and seeds.
- Cells are short, which can be isodiametric, spherical, oval, t- shaped or cylindrical in shape.
- Usually have thick lignified secondary cell walls.
- Occur single or in loose groups.
- Protects the plant from stress and strains from the environment.
- Provide mechanical strength and rigidity.
- Provide grittiness to the pulp of fruits.
Collenchyma
- The cells are elongated and which are circular, oval or polygonal in cross- section.
- Cell wall is unevenly thickened by cellulose at the corners against the intercellular spaces.
- Nucleus is present and therefore the tissue is living.
- Intercellular spaces are generally absent.
- If they contain chlorophyll then they are known as chlorenchyma.
- Found under the skin i.e. below the epidermis in dicot stems.
- Provide mechanical support to the stem.
- Being extensible, these cells readily adapt themselves into the rapid elongation of the stem.

Note:
- In Atriplex plant bladder- like cells attached to epidermis where ions are secreted into a large central vacuole, after cells collapse, ions are deposited on the surface of the leaf.
- In Tamarix, a complex gland of 8 cells, 6 secretory and 2 are basal collecting cells, salts accumulate in micro vacuoles until it is secreted by fusing with plasma membrane, salts can exit through pores in the surface layer.