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In this article we will discuss about the anatomy of funaria.
Cut transverse sections of axis and leaf, stain them in safranin, mount in glycerine and study under microscope.
T.S. Axis:
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1. Internally, there is no much specialization of cells. The axis or stem is differentiated into three different regions, i.e., epidermis, cortex and conducting strand or medulla (Fig. 197A). Stem is circular in outline.
2. Single-layered epidermis is the outermost layer, and consists of small chlorophyll-bearing green cells, but mature stems lack chlorophyll. Stomata are absent. In some cases, epidermis may be double- layered.
3. Below the epidermis is the cortex. It consists of large, thin-walled, parenchymatous cells. At maturity, cortex is observed to be differentiated into outer thick-walled and inner thin-walled cortex (Fig. 198). It may also contain chloroplast.
4. Innermost region of conducting strand or medulla consists of narrow, thin-walled and vertically elongated cells. Its function is to provide mechanical support and help in conduction. There is no xylem or phloem.
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T.S. ‘Leaf’:
1. Leaf consists of central midrib and wings on either side (Fig. 197B).
2. There are no mesophyll or stomata in leaf.
3. Midrib is several-celled thick and contains many thin-walled cells of conducting strand. Thin-walled cells are covered by outer sheath of thick-walled cells.
4. The cells of the wings are large, green, parenchymatous and contain many chloroplasts.
Sex Organs:
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Tease out the tip portions of certain branches, remove the cluster of leaves to bring out antheridia and archegonia, stain them in safranin, mount in glycerine and study:
1. Sexual reproduction is oogamous and takes place by antheridia and archegonia.
2. Funaria hygrometrica is monoecious and autoecious, i.e., archegonia and antheridia develop on two different branches of the same plant.
3. On the apices of the male and female branches develop many antheridia and archegonia, respectively. They are surrounded by perichaetial leaves.
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Antheridia:
1. They are present at the tip of the male branches (Fig. 199A).
2. Antheridia remain surrounded by many perichaetial leaves.
3. Many long, green, hair-like sterile filaments also develop along-with antheridia. These are known as paraphyses.
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4. Each paraphysis consists of 4 to 6 cells with an upper large globular cell.
5. Many antheridia in different stages of development are present on male branch.
6. Each antheridium consists of a massive stalk and a club-shaped body (Fig. 199B).
7. A sterile layer of jacket is present outside each antheridium, the apex of which is closed by one or two opercular cells. Jacket is green when young but becomes red at maturity.
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8. Jacket encloses many androcyte mother cells, each of which divides into two androcytes. Each androcyte metamorphoses into a single biflagellate antherozoid.
Archegonia:
1. These are present at the apex of female branches surrounded by perichaetial leaves.
2 Along with archegonia, many hair-like, long, multicellular paraphyses are present on each female branch.
3. A mature archegonium is a flask-shaped stalked structure with an enlarged venter and a long neck.
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4. Venter remains surrounded by a double-layered wall (Fig. 200).
5. Neck consists of six vertical rows of cells, and encloses 6 to 8 neck canal cells, a ventral canal cell and an egg.
Sporophyte:
Remove a few sporophytes from the tips of female branches, study the external features of its different parts under dissecting microscope and study:
1. It is divisible into foot, seta and capsule.
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2. Foot is conical in shape and remains buried in the upper tissue of the gametophore. Its functions are absorption and anchorage.
3. Seta is very long, cord-like, reddish brown structure, and it held the capsule high.
4. Internally, seta is differentiated into thin-walled cells of conducting strands surrounded by many layers of thick-walled cortex and an outermost layer of epidermis (Fig. 201B).
5. Seta is hygroscopic in nature.
6. Capsule is a pear-shaped structure, the upper portion of which is covered by a cap-like calyptra, which later on falls off.
7. Capsule is erect when young but becomes pendant at maturity.
8. Capsule is differentiated into apophysis, theca and operculum.
9. Apophysis is the basal, green, photosynthetic region of the capsule. Internally, it is differentiated into central columella, surrounded by mesophyll and outermost epidermal layer (Fig. 201 A).
10. Theca is the middle, urn-shaped, spore-producing region of the capsule.
11. The uppermost lid or cap-like region of the capsule is the operculum (Fig 202), which helps in the dehiscence of capsule and dispersal of spores.
12. Operculum remains connected with the capsule by the annulus.
L.S.Capsule:
Cut L.S. of capsule, stain in safranin, mount in glycerine and study:
(A) Apophysis:
1. It is covered by a layer of epidermis, the continuity of which is broken by many stomata (Figs. 203, 204).
2. Below the epidermis is spongy zone of sub- epidermis, the cells of which contain chloroplasts.
3. In the centre is present the central conducting strand, made up of many colourless elongated cells.
(B) Theca:
4. Capsule wall, in this region is bounded by a layer of epidermis with very few or no stomata.
5. Below the epidermis are a few layers of colourless parenchymatous hypodermis, which surrounds one or two layers of green, chlorophyll-bearing spongy cells.
6. Below the green spongy layer is the region of air cavities traversed by many trabeculae. It surrounds the spore sac.
7. Spore sac is bounded externally by a few layers of cells, but only one layer is present on its inner side.
8. Spore sac is filled with the spores formed by the reduction division in spore mother cells.
9. Inner to the spore sac and just in the centre of the theca region is present a solid column of sterile tissue called columella.
(C) Operculum:
10. It is circular, cup-shaped lid, present at the top of the capsule.
11. At the base of the operculum is a ring of epidermal cells called annulus.
Peristome:
With the help of needles remove the operculum of a few mature capsules. Peristomial teeth become visible.
Mount in glycerine and study:
1. If cap-like operculum is removed from the capsule, many tooth-like projections are seen at the top of the capsule. These are peristomial teeth (Fig. 202A, 205).
2. Teeth in the peristome are long, conical and present in one or two rows.
3. In each row there are present 16 teeth.
4. They are hygroscopic in nature. They help in spore dispersal on opening out in dry conditions.
