Ferns & Allies Notes Flashcards
Tracheophytes
Vascular plants - a monophylectic group among land plants.
Vascular plant apomorphies
- lignified secondary cell walls, w/ pits (some)
- sclerenchyma tissue
- tracheary elements (xylem tissue)
- sieve elements (phloem tissue)
- endodermis
- independent, long-lived sporophyte generation
AND, except for the earliest fossil lineages,
- sporophytic leaves associated with a stem to comprise a shoot system
- roots
Vascular plant period of origin
Silurian Period, some 450 mya
The earliest members of tracheophytes belong to three extinct groups, which are known only from fossils.
- rhyniophytes
- zosterophyllophytes
- trimerophytes
Rhyinophyta characteristics
- seedless
- simple, dichotomously branched stems
- no true roots or leaves
- round or elongate terminal sporangia
- homosporous
Cooksonia
The oldest known vascular plant. Its stem was ca. 6.5 cm tall, and its sporangia were round. It became extinct by the mid- Devonian period, ca. 390 mya.
Rhynia
A marsh plant, came next, during the early Devonian (ca. 410-360 mya) . The upright stem was ca. 18 cm tall, ca. 3 mm thick, and dichotomously branched. It possessed a cuticle, was photosynthetic, and had stomata.
Zosterophyllophyta characteristics
- seedless
- simple, dichotomously branched stems
- no true roots or leaves
- round or kidney-shaped lateral sporangia borne on short stalks
- homosporous
- probable ancestors of lycophytes
Trimerophyta characteristics
- seedless
- complex, dichotomously branched stems
- no true roots or leaves
- elongate lateral sporangia borne on short stalks
- homosporous
- evolved from rhyniophytes
- ancestor of ferns and possibly horsetails
Pteridophytes
- This group comprises the extant, seedless vascular plants. At one time, these plants, such as Lepidodendron, dominated the earth. This was especially true during the Carboniferous Period.
- Today, pteridophytes comprise over 13,000 living species. In North America, north of Mexico, there are about 400 species.
Lycopodiophyta apomorphies
- endarch protoxylem of roots
- exarch protoxylem of stems
- lycophyll (microphyll) leaf type. This is a relatively small leaf that possesses only a single strand of vascular tissue. It is usually associated with stems that have protosteles. Leaf gaps are not produced by lycophylls.
Family Lycopodiaceae characterics
- common names: club moss, ground pine, running cedar
- aboveground stems are dichotomously branched
• belowground stems (rhizomes) possess adventitious roots
- sporangia are associated with sporophylls
- sporophylls are often aggregated into a strobilus
- homosporous
* Lycopodium - common in North America. Certain species were collected for making Christmas wreaths, and the dry spores were once used as flash powder and condom lubricants.
Family Selaginellaceae characteristics
- common name: spike moss
- aboveground stems are dichotomously branched
- belowground stems (rhizomes) possess adventitious roots
• leaves possess a ligule
- microsporangia are associated with microsporophylls, megasporangia are associated with megasporophylls
- sporophylls are often aggregated into a strobilus
- heterosporous
* most Selaginella sp. live in tropical regions
Family Isoetaceae characteristics
- common name: quillwort
- belowground stems are short, erect, and cormlike; and possess adventitious roots
- leaves are long and quill-like, and each possesses a ligule
• microsporangia and megasporangia are sunken in the bases of the leaves
• heterosporous
* Isoetes - an emergant plant of shallow ponds.
Euphyllophytes
• sister group of lycophytes
• comprises remaining tracheophytes (vascular
plants)
- 30-kilobase inversion in the large single-copy region of chloroplast DNA
- exarch protoxylem of roots
- euphyll (megaphyll) leaf type. This is a relatively large leaf that usually possesses several strands of vascular tissue, as well as a leaf gap.
Monilophytes
• common name: ferns (in a broad sense)
• monophyletic group comprising members of
5 orders
- mesarch protoxylem of stems
- most members possess a stem vasculature known as a siphonolostele
Steles
Another name for the vascular cylinder is the stele. There are several types of steles ranging from primitive to advanced.
Protostele
- A protostele is the simplest and most primitive type of stele. It consists of a solid cylinder of vascular tissue in which the phloem either surrounds the xylem (haplostele = A, actinostele = B) or is interspersed within it (plectostele = C).
- Protosteles are found in most roots. In stems, protosteles are usually found in extinct vascular plants, psilophytes, and lyco
Siphonostele
A siphonostele is characterized by having a pith surrounded by vascular tissue. The phloem tissue may be found only on the outside of the xylem (ectophloic = D) or on both sides (amphiphloic = E). A dictyostele (F) is characterized by a system of strands of vascular tissue around a pith.
Eustele
A eustele (G) is also characterized by a system of strands of vascular tissue around a pith. An atactostele (H) is characterized by vascular tissue scattered throughout the pith. These two stele types are found in seed plants.
What are the shared apomorphies of Ophioglossales and Psilotales?
- roots unbranched, root hairs absent
- gametophyte subterranean, mycorrhizal
Order Ophioglossales
• common name: ophioglossoid ferns
• fronds are dimorphic, with a sterile segment
and a fertile segment
• eusporangium (large sporangium with wall comprising more than one cell layer; formed from more than one epidermal cell; may have 128-several thousand spores; no annulus)
Family Ophioglossaceae
- common names: adder’s tongue, grape fern
- sporangia aggregated into an upright fertile region or spike
- homosporous
Ophioglossum (adder’s tongue)
- several species in North America
- record for most chromosomes (n=621)!
Order Psilotales
- common name: psilophytes
- stems dichotomously branched
- enations
- lack true roots (probably lost)
- absorptive rhizoids arise from rhizome
- sporangia arranged in groups of 3’s (synangia)
- homosporous
Family Psilotaceae
* Tmesipteris (ca. 10 species)
• Australia, New Zealand, Philippines, New
Guinea
• members have larger leaf-like appendages than Psilotum.
* Psilotum (2 species)
- common name: whisk fern or whisk broom
- found naturally in the warmer parts of the southeastern United States
Order Equisetales
- common names: equisetophytes, spenophytes, horsetails, scouring rushes
- homosporous (spores possess chloroplasts)
- four major apomorphies
- stems conspicuously jointed, ribbed, often hollow, unbranched or with whorls of branches
- leaves greatly reduced to a whorl of scales forming a sheath at the nodes.
- strobili terminal; sporangia attached to sporangiophores
- spores with four elaters, which coil and uncoil in response to changes in humidity
*Calamites *
An equisetophyte that took the form of a large tree and was widespread ca. 300 mya during the Carboniferous period. Much of our coal comes from the remains of this plant.
- several species are native to N. America
- rough silica- containing stems may have been used by settlers to clean pots and pans.
Order Marattiales
- common name: marattioid ferns
- large pinnate or bipinnate fronds that have circinate vernation (unrolling of the frond during development; produces a fiddlehead)
- eusporangiate
- polycyclic siphonostele
Order Polypodiales
- common names: leptosporangiate ferns
- leptoporangium (small sporangium with annulus; formed from one epidermal cell; may have 64-128 spores)
- sporangia usually grouped into clusters know as sori
- sori may be indusiate or exindusiate
- false indusia are present in some groups
- sporangia possess an annulus, which helps in spore dispersal
Family Polypodiaceae
- common name: polypody
- rhizomes creeping, covered with scales; leaves often simple though usually lobed
- sporangia forming a mound-like sorus, exindusiate
* Polypodium (75 species)
- common in the eastern United States
- strobili have micro- & megasporophylls with micro- and megasporangia
Family Osmundaceae
- common name: royal fern, cinnamon fern, interrupted fern
- leaves pinnately compound, dimorphic, the fertile pinnae differentiated from the sterile pinnae; sporangia large
* Osmunda (14 species) - common in N. America
Family Schizaeaceae
- common name: climbing fern
- vines and grass-like tufted plants
- leaves dimorphic, some produce sporangia, others do not
* Lygodium (60 species) - found in the eastern United States as far north as Michigan
Family Pteridaceae
- common name: maidenhair fern
- pinnae dichotomously veined
- sori along the veins, or along the reflexed margins of the pinnae (false indusia)
* Adiantum (200 species) - found throughout much of the eastern United States
Family Dennstaedtiaceae
- common name: bracken fern, hayscented fern
- rhizome creeping; leaves large and divided
- sori along leaf margin or on back of leaf
* Pteridium (1 species) - common name: bracken fern
- found over much of the world
- marginal sori covered by rolled-over leaf blade (false indusium)
Family Aspleniaceae
- common name: spleenwort
- sori round or elongate, indusia kidney- shaped or linear; spores surrounded by a wrinkled or winged sheath-like covering
* Asplenium - both temperate and tropical regions
Family Dryopteridaceae
- common name: wood fern
- sori borne on the veins or at the vein tips
* Dryopteris (150 species) - both temperate and tropical regions
• marginal sori covered by kidney-shaped indusia
* Onoclea - sensitive fern
• sori completely enclosed by leaf material
Family Marsileaceae
- common name: water clover
- aquatic; ground-level stolons produce the leaves, each leaf has two leaflets
- sporocarps produced
* Marsilea (60 species) - water fern
- microsporangia and megasporangia are in sori, which are in sporocarps (viable up to 30 years)
- heterosporous (microspores and megaspores)
- microsporangium has 32-64 microspores
- megasporangium has 1 megaspore
Family Salvineaceae
- common name: salvinia, water spangles
- floating aquatics; leaves in whorls of three, two floating and simple, and one very divided and dangling, resembling a root
- sporocarps produced
* Salvinia - mainly tropical America and Africa
• each plant has two floating leaves and one dissected root-like submerged leaf
Family Azollaceae
- common name: mosquito fern
- floating aquatic; leaves in two rows, scale-like and overlapping, harboring cyanobacterium Anabaena azollae (nitrogen fixation)
- sporocarps formed
* Azolla
- often takes on a reddish or reddish green color
- temperate and tropical areas
