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33 Cards in this Set
- Front
- Back
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Classify EQUISETUM
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D- Eukarya
K- Plantae P- Tracheophyta C- Sphenopsida O- Equisetales F- Equisetaceae G- Equisetum S- |
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Discuss the MORPHOLOGY and GROWTH HABIT of EQUISETUM
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-undergound rhizome systme by means of which they spread vegetatively
-aerial shoots arise from rhizome (pretty short) -shoot is truly monopodial -leaves occur in whorls and are non-photosynthetic (ACHLOROPHYLLOUS) -rhizomes are very similar to the aeiral shoots but have fewer branches at the nodes -distinct nodes therefore stem has a jointed appearance -elongates via INTERCALARY MERISTEMS -branches arise in whorls ar some distance from the shoot apex and DO NOT result from any branching at the apical meristem -stems are ridged and grooved, and the leaves at each node ordinarily arise above the ridges of the internode below and alternate at successive nodes |
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Discuss the ANATOMY of EQUISETUM.
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-develops only primary tissues
-no terminal branching -branches of the shoot arise at the nodes from branch meristems alternating with leaf bases, they actually emerge by perforating the fused leaves -lateral roots have their origin in the pericycle of the parent root as in seed plants Dermal System -consists of an epidermis with cuticle and stomata -stomata are found in the grooves of the stem -cortical layer conists of sclerenchyma which is thickest beneath the stem ridges and absent under he stomata -under sclerenchyma is a region of photosynthetic cortical tissue with intercellular spaces -under the grooves are large lacunae or canals (VALLECULAR CANALS) which are possibly an aerating device Vascular System: -f'd up -in internode, a ring of distinct bundles containing very little xylem -endarch protoxylem is ripped out during elongation, as in the stem of corn, leaving a small lacuna or canal (CARINAL CANAL) -the bundles are underneath the ridges of the stem and thus correspond to positions of he leaves of the node above, each of which has a single leaf trace -at the node is a continuous ring of xylem and phloem, leaf traces depart from this ring at the node without leaving a gap -bundels in the internodes are not really leaf traces or their downward extensions, and the stele cannot be a eustele Rhizomes: -rhizomes of some spp contain vessels in the xylem of the internodes, another case of the sporadic, independent origin of vessels -the roots often contain sclerenchyma in their cortex and have an exarch protostele (not pith) -large metaxylem vessel element in the centre |
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Discuss the SPOROPHYTE of EQUISETUM.
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-homosporous life cycle
-some spp have separate vegetative and fertile shoots. The fertile shoots are unbranched, without chlorophyll and wither awar soon after spores are shed -STOBILI (cones) are produced terminally on main or lateral shoots -axis, which is a continuation of the shoot, bears the distinctive sporangiophores in whorl instead of leaves -since there is very little elongation of the axis, these spore producing appendages, the SPORANGIOPHORES are close together -this type of vascular supply suggests that the sporangia are borne at the tip of a branch (like Psilotum), not on the leaf (like Lycopsida) -sporangiophores are umbrella shaped (PELTATE), each bearing a number of sporangia attached to the underside of the flattened tip and pointing in toward the cone axis -in immature cones, the expanded tips of the sporangiophores fit together so that the sporangia are enclosed; at maturity, they separate and the spores, shed from the sporangia, are able to sift out -spores are covered in ELATERS, uncoiling when dry, coil when moist. Cause the spores to clump, therefor gametophytes are close together, favouring cross fertilization -spores are bright green because of chlorophyll, an unusual feature in the vascular plants |
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Discuss the GAMETOPHYTE of EQUISETUM.
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-green and photosynthetic
-each has a basal disc or pad with rhizoids from which upright lobes arise -can get pretty big Sex Organs: -some confusion here, some have concluded that there are separate male and female gametophytes which develop from spores and do not differ in size (HETEROTHALLISM instead of HETEROSPORY) -as the gametophytes develop, some produce archegoina on the basal pad, among the upright lobswe with their necks protruding; others that are usually smaller in size, initiate antheridia producing numerous multiflagellate sperm which must hav water in which to swim in order to effect fertilization -most of the initially female gametophytes later give rise to antheridia at the margins and are thus BISEXUAL -most male gametophytes stay that way, but may also become bisexual later on |
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Discuss the EMBRYOLOGY of EQUISETUM.
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-shoot apex arises early from the half of the embryo facing the archegonial neck and quickly initiates the first whorl of leaves
-the root apex arises from the inner half of the embryo which it shares with a rather poorly developed foot -there is no suspensor at all |
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List 5 characteristics of Sphenopsida.
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-appendages whorled at nodes
-stem with distinct nodes and internodes - jointed or articularted -sporangia reflexed on sporangiophores -lateral branches alternate with leaves -stem is often, but not always, ribbed and grooved |
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What are EQUISETITES?
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-fossilized forms of Equisetum
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Classify CALAMITES
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D- Eukarya
K- Plantae P- Tracheophyta C- Sphenopsida O- Equisetales F- Calamitaceae G- Calamites S- |
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What are some defining characteristics Calamites?
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-they are essentially overgrown horsetails
-abundant in the Carboniferous and extended into the Permian -morphology of outer stem is still questioned because fossils are casts of the inside -developes more secondary xylem than lepidodendrids -vascular cambium was unifacial -leaves were usually several centimeteres in length and are believed to have been photosynthetic -had Annularia -generally homosporous -spores had elaters |
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What is the FORM GENUS ANNULARIA?
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-whorled leaves on Calamites
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What is the FORM GENUS CALAMOSTACHYS?
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-the cones of Calamites
-had alternating whorls of sterile bracts and sporangiophores at successive nodes |
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What are BRACTS?
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-a modified, usually reduced leaf like structure
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What are some characteristics to the Order SPHENOPHYLLALES?
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Morphology
-name means 'WEDGE LEAF' -small, slender plants, with shoots seldom more than a centimeter in diamter -dichotomous branching of the axis Anatomy -exarch protosele with a triangular cross sectional shape which soon became surrounded by a relatively large amount of secondary xylem from an active vascular cambium -cambium produced secondary xylem and phloem -also developed a PERIDERM -whorled leaves and the structure of the cones show clearly that they belopn in the same class as Equisetum and Calamites although their anatomy is very different -homosporous, but very complex |
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What are some characteristics to the Order PSEDUDOBORNIALES?
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-not much is known
-monopodial -tree like plant up to 15-20m high, with distinct nodes and internodes and with a basal diamter up to 60cm -3 orders of branching and the ultimate branchlets bore whorls of 4 leaves which were dichotomously branched, highly dissected and up to 6cm long -at the tips of fist order branches, in the upper resions of the plant, cone like strucures were borne; consisting of whorls of sporangiophores and sterile bracts |
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What are some characteristics to the Order Hyeniales?
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Morphology:
-most likely the first sphenopsid (ie:origin of the Sphenopsida) -include 2 genera: Hyenia (smaller) and Calamophyton (bigger) -have sterile and fertile appendages which appear to be homologous -dichotomously branched and which tend to be whorled, but not very precisely -sporangia are recurved (ie: directed back toward the axis in characteristic sphenopsid fashion) -number of main branches seem to arise at or near a common point (DIGITATE BRANCHING) as a result of repeated, closely spaced dichotomies -branching appendages do not look like microphylls of the lycopsid type, they seem more like small branches **Due to some evidence from Ibyka vascular systems, the stele of Equisetales can now be interpreted as the result of the medullation (pith formation) of a much lobed protostele, that is, as a dissected siphonostele** **suggests that the leaves of the Sphenopsida are not equivalent to the enation leves or microphylls of the Lycopsida. Tather, they represent a modification of very minor portions of the branching shoot system** |
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What Questions should we be asking to relate Sphenopsida (or anything) to other vascular plant groups?
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1) What is the nature of the leaves?
-modified lateral branches (megaphylls or microphylls)? 2) What is the nature of the sporangiophores? -are they modified branches as the apparently terminal position of sporangia suggests, or are thy modified leaves as the alternating whorls of leaves(bracts) and sporangiophores in calamite cones seems to indicate? -are the leaves and sporangiophores homologous organs? 3)What is the origin of the stele? |
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What are some characteristics to the Class FILICOPSIDA?
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-includes a diverse assemblage of ferns and fern like plants, both living and exting
-believed to have its origin amont he Trimerophytopsida through the further development of he pseudomonopodial branching pattern and the transformation of portions of the branching system into a MEGAPHYLL -sporangia camt to occupy both marginal and abaxial positions on leaves rather than on terminal end -generally lack secondary tissues |
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Regarding only LEAVES, where does Sphenopsida lie in evolution?
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-leaves of the SPHENOPSIDA lies in an intermediate position between the MICROPHYLLS of the LYCOPSIDA and the MEGAPHYLLS of the FILICOPSIDA
-like megaphylls they are modified from parts of the branching system, butvery minor parts in comparison to the size and omplexity of the branches which became MEGAPHYLLS -like microphylls , they have a minor infulence upon the stele of the axis to which they are attached and they leave no gaps, but they have a very different origin... -they should have a name of their own |
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What are some characteristics to the Order CLADOXYLALES?
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-morphologically similar to the trimerophytes, they are characterized bhy a lobate to highly dissected protostele which resembles that of the Hyeniales
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What are some characteristics of the Order COENOPTERIDALES?
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-possess features strongly suggestive of the Filicales and probably represent the emergence of the evolutionary line leadin to the modern ferns
-body form ranged from rhizomatous to upright and some appear to have had a scrambling or vine like habit -fronds were indterminate in growth and very shoot like so that the distinction between leaf and stem is difficult to make -sporangia were borne terminally on ultimate appendages or marginally or abazially on laminated appendages -sporangia weree large with many spores but sometimes had a dehiscence mechanism sugestive of modern ferns |
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What are ULTIMATE APPENDAGES?
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-originate on stems or branches
-usually small -ultimate because they exhibited determinate growth |
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What are some characteristics to the Order Filicales?
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-includes almost all of the leptosporangiate ferns and forms the bulk of the living ferns
-unless reproductive structures are preserved, which they often are not, it is impossible to distinguish the fern groups, or even o be ure that the foliage is not that of a seed fern |
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Discuss the MORPHOLOGY of FILICALES
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-range from delicate filmy ferns (with a leaf lamina only 1 cell thick) to small trees 60 to 80 ft tall (with big leaves)
-may have either an upright axis or a horizontal rhizomatous one -rhizomes may be either subterranean or at the surface (STOLONS) -short shoots -epiphytes -branching is terminal, either dichotomous or pseudomonopodial, or it may be monopodial with the formation of lateral buds -large, pinnately compound frond -leaves develope via circinate vernation |
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Discuss the ANATOMY of FILICALES
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-none of the Filicales have secondary growth
-have large and complex steles that show wide range of forms (commonest type being the AMPHIPHLOIC DICTYOSTELE) -in all cases, the young sporophyte begins with a protostele and the complex stele develops later as the stem enlarges |
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Define AMPHIPHLOIC
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-a siphonostele which has an inner band of phloem next to the pith as well as outer phloem
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Discuss the SPOROPHYTE of FILICALES
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-homosporous and their sporangia are called LEPTOSPORANGIA, free sporing plants
-leptosporangia have an extremely delicate structure and a very superficial origin -they are initiated from a single superficial cell which divides periclinally -the outer derivative of this division produces the whole sporangium; the inner cell does not participate -leptosporangia have been evolutionarily reduced in size and the number of spores is correspondingly limited -low number of spores, therefor increased number of sporangia per sorus... spreads the aging process... doens't blow all its load in one shot |
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Define EUSPORANGIUM
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-one or more cells divide periclinally, the outer derivatives producing the wall while the inner give rise to the sporogenous tissue
-common in all vascular plants and some fern groups |
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Define RENIFORM and PELATATE indusium
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RENIFORM
-kidney shaped indusium -a lateral flap of tissue, by a cup like indusium which grows up around the sorus PELTATE -indusium that grows up from the centre |
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What are some characteristics of the Order OPHIOGLOSSALES?
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-have typical eusporangia which are large, contain many spores, and have no special opening device (annulus)
-gametophytes are large, fleshy and subterranean, with an endophytic mycorrhizal fungus -the only fern with a vascular cambium is Botrychium -2 parted fronds with fertile and sterile regions |
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What is the only Fern with a vascular cambium?
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Botrychium
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What are some characteristics of the Order MARATTIALES?
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-small but distinct group of ferns that are entirely tropical
-eusporangia are large and many spored -gametophytes are surface living, green, large and rather long lived -sporangia are borne n sori on the abaxial surface of the leaves ad are fused into SYNANGIA Psaronius -a tree up to several meters tall with fronds as much as 2m long -stem contained a highly complex stele in which up to 10 concentric cylinders of vascular tissue developed, one inside the other -the stem was densely sheathed in a mantle of adventitious roots which, at the base, could be as much as 30cm thick -roots are embedded in pseudotissue composed of tightly appressed root hairs produced by the multitude of roots -this mantle provided the main support for the plant, whose slender trunk has no secondary growth |
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What are some characteristics of the Orders MARSILEALES and SALVINIALES?
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-these two orders of ferns are highly specialized and show considerable morphological reduction
-homosporous, but a few of the extinct Carboniferous ferns heterosporous, as are these two small groups of living, leptosporangiate ferns -in the heterospory ferns, the development of the gametophyte is endosporal -spores produced in SPOROCARP -sporocarp is extremely resistant and commonly remains viable for 20-30yrs -function to carry the plant over unfavourable periods (ie: drought) -if placed in water, the sporocarps will ultimately germinate -sporocarp is believed to represent a single pinna or leaflet bearing sori on the abaxial surface and folded abaxially so that the sori are enclosed -there are 2 rows of sori and each sorus is covered by a sac like indusium -in water, the sporocarp craxks open due to the swelling of a gelatinous, transparent inner structure called a SOROPHORE which carries the sori out into the surrounding medium -gradually all of the tissue disintegrates and the spores are released -male gametophyte is an antheridium -female gametophyte is a large basal cell with abundant stored food and a protruding apical cap which is little moe than a single archegonium -after fertilization, the embryo develops rapidly and in 2-4 days, te first leaf is several mm long and easily visible |
