Name Section Number EXERCISE 8 Seedless Vascular Plants: Club Mosses and Ferns P
ID: 258760 • Letter: N
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Name Section Number EXERCISE 8 Seedless Vascular Plants: Club Mosses and Ferns Post-Lab Introduction 1. List two features that distinguish the seedless vascular planits from the bryophs 2. After consulting a biological or scientific dictionary, explain the derivation from the Ge of te wrd symmbiosis 8.1 Phylum Lycophyta: Club Mosses 3. Both Lyecopodisum and Episctum have strobis rocots, and thinoomes Wihat did you learm in s ecet enables you to distinguish these two plants? Examine the photo at the right. (a) Give the genus of this plant 4. (b) Label the structure indicated. 5. Some species of Lyopodiom produce gametioghytes that grow beneath the surface of the soil, while others grow on the soil surface. Basing your answer on what you've learmed firom other plants in this exercise, predict how each respective type of Lyycopodium gametophyte might obtain its nutritional needs. D3x 8.2 Phylum Moniliophyta, Subphylum Psilophyta: Whisk Ferns 6. Using a biological or scientific dictionarg, or a mefir nestfthercik, šãetermine the meaning of the root word psila, and nelate it to the appearance of Psiletum 135Explanation / Answer
1)
2)Symbiosis is the relationship between two types of animal or plants in which each provides for the other the conditions necessary for its continued existance.
The word symbiosis came from German and New latin from greek symbios means syn -with bios - life. Symbiosis means state of living together.
8.1)
3) The Lycopodium sporophyte develops an underground rhizome system. A rhizome is an underground stem. This rhizome produces true roots along its length. The sporophyte is also competitive in fairly moist soils, though some species are specialized for desiccating environments. The rhizome system will send up aerial shoots. These stems grow up into the light and carry out photosynthesis.
The vascular system in both rhizome and aerial stems is called a plectostele (sometimes a root-like actinostele). It is a solid vascular cylinder with exarch xylem maturation. The ridges of xylem in the actinostele and the edges of the ribbons of xylem in the plectostele are the location of protoxylem. The phloem completely surrounds the actinostelic forms and penetrates the ribbon-like xylem areas of the plectostele. Outside the stele is a cortex for storage in the rhizome and for limited photosynthesis in the aerial shoot. The epidermis of the aerial shoot is cutinized and produces stomata for gas exchange.
"more advanced" lycophytes (such as Lycopodium obscurum) the sporophylls are produced in a terminal cluster called a strobilus. These sporophylls often lack chlorophyll and show through the yellow colors of the sporangia in their axils. The strobilus is sometimes called a "cone" in casual settings.
Further-advanced lycophytes (such as L. clavatum) produce a cluster of strobili at the shoot apex...increasing the number of spores that can be produced by the sporophyte.
Finally the most-advanced lycophytes (such as L. complanatum produce a very long stem section below the strobili, elevating them higher into the wind. This will provide a better distribution of spores downwind.
The aerial shoot does have leaves, but they are very small. These are called microphylls because they have just a single vascular bundle running along their length. The microphylls have photosynthetic cortical mesophyll, and so are very bright green in color. The microphylls are generally spiral in arrangement, though some of the leaves may be small and appressed against the stem epidermis in some species. Because of the leaf arrangement and appearance, Lycopodium species have common names such as "club moss" or "princess pine" or "ground pine" or "running pine." All of these describe some superficial resemblances of these sporophytes of other plants (more or less primitive) to Lycopodium.
The Equisetum sporophyte develops an underground rhizome system. The rhizome produces true roots along its length. The sporophyte is also competitive in fairly moist soils, though some species are specialized for desiccating environments. The rhizome system will send up aerial shoots. These stems grow up into the light and carry out photosynthesis.
The vascular system in both rhizome and aerial stems is a eustele. It is a ring of vascular bundles. These bundles consist of bundle of phloem with xylem on the radial and inner tangential sides. The xylem maturation is endarch. So this is an advanced system in terms of stele and xylem maturation, but rather primitive in the xylem/phloem arrangement. The vascular system is surrounded by an endodermis. Outside that is a cortex for storage in the rhizome and for extensive photosynthesis in the aerial shoot. The epidermis of the aerial shoot is cutinized and produces stomata for gas exchange. But the most unique feature of this epidermis are cells that are invested with much silicon dioxide. This deposit is very glass-like. Running through a stand of Equisetum hyemale sounds like shattering glass in a vague way.The aerial shoot does have leaves, but they are very small and generally are not photosynthetic. These are microphylls and have just a single vascular bundle running along their length. The microphylls are whorled arrangement at the nodes of the stem. In Equisetum hyemale, the stem has very strong apical dominance and so it is a stem with the tiny leaves appressed against the stem epidermis.
At the apical bud of the stem, or at the apex of a fertile stem, a strobilus forms. This strobilus looks superficially like a pineapple with hexagonal scales covering the surface. Each of these scales is the outer surface of a sporangiophore. This scale is attached to the axis of the strobilus by the stalk of the sporangiophore. All around this stalk, and attached to the underside of the scale are several sporangia with sterile jackets. The scale shrinks in diameter and the stalk grows and curves upward as the strobilus matures. When the sporangia dry out, they crack open and release the spores to the wind. The spores of Equisetum each have four wall strips, called elaters, that reflex outwards to push the spores away from each other. This assures that the spores do not clump and make it into the wind for dispersal.
4)a) Lycopodium
b) Strobilus
5) The gametophyte is nourished by the parent sporophyte. young sporophyte produces a multicellular structure called the FOOT which remains embeded in the tissues of gametophyte withdrawing nutrients.
8.2)
Pisilo means bare,naked , smooth and bald
Pisilotum are genus of fern like vascular plants that lack true roots and leaves and stems have conducting tissues.
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