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In this article we will discuss about vegetative structures of agaricus.
1. Vegetative mycelium grows within the soil.
2. The primary mycelium is septate, haploid, short lived, and each cell contains oil globules, vacuoles and one nucleus.
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3. The secondary mycelium is dikaryotic and long-lived.
4. The hyphae of the secondary mycelium are long, branched and remain twisted to form a thick hyphal cord, called the mushroom’s body or basidiocarp.
Button Stage and Its Longitudinal Section:
1. The fruiting-bodies arise as small, white, globular, apical swellings (Fig. 102) on the branches of the subterranean mycelial strands.
2. These small tiny knots represent the common “Button-Stage” of the fungus.
3. The dome-shaped upper portion is known as pileus (Fig. 103).
4. The lower hyphae constitute the stalk or stripe.
5. The margins of the pileus are connected with the stipe with the help of a membrane called inner veil or velum.
6. There is present a constriction between stipe and pileus.
7. Two gill-chamber cavities are present, one on either side of the pileus.
8. From the roof of these cavities arise many gills or lamellae.
9. Button stage is a developmental stage of the fruiting body of Agaricus.
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Mature Fruiting Body:
1. The basal underground mycelial portion is known as rhizomorph, from which develops the basidiocarp or fruiting body.
2. The basidiocarp is differentiated into a long stalk-like stipe and an upper cap-like pileus (Fig. 104).
3. The stipe is fleshy, and made up of pseudoparen-chymatous mass of hyphae. It gives support to the pileus.
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4. Pileus is an umbrella-shaped structure, the underside of which is lined by many gills.
5. On the stipe is present a membranous ring of velum or annulus, which, in the early stages, remains in contact with the pileus.
T.S. Through Gills:
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1. Three types of gills are present, which vary only in their size. These are known as long gills, half- length gills and quarter-length gills (Fig. 105B).
2. In each gill, three different layers are present, i.e., trama, sub-hymenium and hymenium (Fig. 106).
3. The trama consists of many anastomosing, interwoven sterile hyphae. It is central in position.
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4. The hyphae of trama region develop into a compact hypodermal layer on its either side. This is known as sub-hymenium.
5. The hyphae of the sub-hymenial layer terminate into the superficial layer of the gills called hymenium.
6. The hymenium (Figs. 106, 107) consists of many club-shaped cells of two types, of which some are fertile cells and called basidia, and others are sterile cells and called paraphyses.
7. From each basidium develops four basidiospores.
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8. Basidiospores remain attached with the basidium with the help of sterigmata (sing, sterigma).
9. Each basidiospore is a purple coloured, oval and uninucleate structure.
