What are microphylls and megaphylls?
Microphylls are the leaves with a single vein, which is unbranched. They also do not contain leaf gaps. Generally, microphylls occur in lycophytes and horsetails. In contrast, megaphylls are the other type of leaves with multiple veins and leaf gaps. They occur in angiosperms, gymnosperms, and fronds of ferns.
Where do microphylls occur in plants?
Furthermore, microphylls occur in lycophytes, including club moss, quillworts, and selaginella. They also occur in horsetails. However, horsetails along with whisk ferns and true ferns make the phylum Pteridophyta. Generally, the members of Lycophyta and Pterophyta are seedless vascular plants.
What are the characteristics of conifers?
Conifers are woody plants and most are evergreens. The leaves of many conifers are long, thin and needle-like, other species, including most Cupressaceae and some Podocarpaceae, have flat, triangular scale-like leaves.
Are conifers gymnosperms or evergreens?
Conifers are by far the most abundant extant group of gymnosperms with six to eight families, with a total of 65-70 genera and 600-630 species (696 accepted names). Conifers are woody plants and most are evergreens.
Do gymnosperms have megaphylls?
Lycophytes have microphylls (leaves with single unbranched veins), while other vascular plants (ferns, gymnosperms and angiosperms) have megaphylls (leaves with multiple branched veins).
Do pine trees have microphylls?
Ground Pine (Lycopodium obscurum) It has simple leaves (microphylls) with a single, unbranched vein running their length. A cone-like structure (a strobilus) is borne at the tip of a vertical branch. The strobilus consists of modified leaves which bear sporangia in their axils.
Do seed plants have megaphylls?
Seeds are easily dispersed structures developed from a zygote and enclosing an embryonic sporophyte. All plants with seeds also possess megaphylls, leaves with branched veins whose bases interrupt the vascular bundle to form a leaf gap.
Do conifers have Heterospory?
Conifers are heterosporous, generating two different types of spores: male microspores and female megaspores. These spores develop on separate male and female sporophylls on separate male and female cones. In the male cones, microspores are produced from microsporocytes by meiosis.
Which type of plant has megaphylls?
In contrast, megaphylls are the other type of leaves with multiple veins and leaf gaps. They occur in angiosperms, gymnosperms, and fronds of ferns.
Where are megaphylls found?
Megaphylls are seen in ferns and more derived vascular plants. In addition to photosynthesis, leaves play another role in the life of the plants. Pine cones, mature fronds of ferns, and flowers are all sporophylls—leaves that were modified structurally to bear sporangia.
What is the difference between microphylls and megaphylls?
Microphylls are defined as leaves of small size, with simple venation (one vein) and associated with steles that lack leaf gaps (protosteles). By contrast, megaphylls are defined as leaves of generally larger size, with complex venation and associated with leaf gaps in the stele [3].
Are all ferns megaphylls?
If ferns are considered a monophyletic group (Figure 1), then all fern leaves are considered to be megaphylls or at least derived from megaphyllous ancestors. Megaphylls then are present in seed plants and ferns and there are several competing theories regarding their evolution and origin.
Do ferns have megaphylls?
Ferns are non-flowering plants with large leaves called megaphylls that reproduce by spore formation. Spores are reproductive cells that are capable of maturing into an adult plant without fusing with other cells. Ferns are in the plant division, Pteridophyta, and to date there are 10,400 known species of true ferns.
What are the characteristics of conifers?
All but 15 types of conifers are evergreen, one of the familiar characteristics of this group of plants. They grow with a straight, central trunk bearing circles of horizontal branches, and the branching may become increasing complex as the tree gets older. Conifers also have a wide variety of distinctive bark.
What is special about coniferous trees?
Coniferous forests consist mostly of conifers, which are trees that grow needles instead of leaves and cones instead of flowers. Conifers tend to be evergreen—they bear needles all year long. These adaptations help conifers survive in areas that are very cold or dry.
What is the structure of conifers?
Conifers comprise a monophyletic group of highly branched trees or shrubs with simple leaves, the latter a possible apomorphy shared with the ginkgophytes (Figure 5.1). Leaves of conifers are often linear, acicular (needle-like), or subulate (awl-shaped; see Chapter 9), although they are sometimes broad and large.
Where is microphylls found?
This type of leaf pattern is similar to ferns. This unique leaf pattern is called microphylls. Lycophytes produce spores for reproduction. Thus, microphylls are found in lycophytes.
What is the difference between megaphylls and microphylls?
Microphylls are defined as leaves of small size, with simple venation (one vein) and associated with steles that lack leaf gaps (protosteles). By contrast, megaphylls are defined as leaves of generally larger size, with complex venation and associated with leaf gaps in the stele [3].
Are needles microphylls?
Conifer leaves are needle or scale-like. They result from the downsizing of true megaphylls and unlike the microphylls of lower plants they are connected to the vascular system of the stem.
Which plants does not showing leaf gap?
Plants. Bryophytes (liverworts, hornworts, and mosses) are nonvascular plants; i.e., they lack vascular tissues (phloem and xylem) as well as true leaves, stems, and roots.
Where are conifers native to?
Zamia integrifolia, a cycad native to Florida. Conifers are by far the most abundant extant group of gymnosperms with six to eight families, with a total of 65–70 genera and 600–630 species (696 accepted names). Conifers are woody plants and most are evergreens. The leaves of many conifers are long, thin and needle-like, other species, ...
What is the name of the group of seed-producing plants that includes conifers, cycads?
Cycadophyta – Cycads. Gnetophyta – Gnetum, Ephedra, Welwitschia. Encephalartos sclavoi cone, about 30 cm long. The gymnosperms, also known as Acrogymnospermae, are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος ( γυμνός, gymnos, ...
What are the two types of spores?
Two spore types, microspores (male) and megaspores (female), are typically produced in pollen cones or ovulate cones, respectively. Gametophytes, as with all heterosporous plants, develop within the spore wall. Pollen grains (microgametophytes) mature from microspores, and ultimately produce sperm cells. Megagametophytes develop from megaspores and ...
What is the name of the tree that has a fern-like morphology?
The fossil record of gymnosperms includes many distinctive taxa that do not belong to the four modern groups, including seed-bearing trees that have a somewhat fern -like vegetative morphology (the so-called "seed ferns" or pteridosperms ).
How do megagametophytes develop?
Megagametophytes develop from megaspores and are retained within the ovule . Gymnosperms produce multiple archegonia, which produce the female gamete. During pollination, pollen grains are physically transferred between plants from the pollen cone to the ovule. Pollen is usually moved by wind or insects.
What is the largest group of gymnosperms?
By far the largest group of living gymnosperms are the conifers (pines, cypresses, and relatives), followed by cycads, gnetophytes ( Gnetum, Ephedra and Welwitschia ), and Ginkgo biloba (a single living species). About 65% of gymnosperms are dioecious,, but conifers are almost all monoecious. Some genera have mycorrhiza, fungal associations ...
What is the non-encased condition of seeds?
The non-encased condition of their seeds contrasts with the seeds and ovules of flowering plants ( angiosperms ), which are enclosed within an ovary. Gymnosperm seeds develop either on the surface of scales or leaves, which are often modified to form cones, or solitary as in yew, Torreya, Ginkgo.
What are megaphylls in plants?
What are Megaphylls. Megaphylls are the other leaf structures that occur in vascular plants. They are derived from the euphyllophyte structures independently. Therefore, microphylls and megaphylls are analogous structures which have different anatomical structures but, similar functions.
What is the difference between microphylls and megaphylls?
The main difference between microphylls and megaphylls is that microphylls are leaves having a single, unbranched vein, whereas megaphylls are leaves with multiple veins. Furthermore, in microphylls, the single vein originates from the protostele without having a leaf gap while megaphylls contain leaf gaps. Moreover, microphylls are the leaves, ...
What are the two types of leaf structures?
Microphylls and megaphylls are two types of leaf structures, which occur in vascular plants. Both develop independently from euphyllophyte leaf precursor structures. They are not homologous structures. Moreover, they differ from each other by means of leaf veins and leaf gaps.
What are the two types of structures that occur in leaves of vascular plants?
Moreover, microphylls are the leaves, which occur early in the fossil record up to date while megaphylls develop independently from euphyllophyte leaf precursor structures. Microphylls and megaphylls are two types of structures that occur in leaves of vascular plants.
What is a microphyll?
Definition. Microphylls refers to a type of very shortleaf, such as in moss or clubmoss, with a single unbranched vein and no leaf gaps in the stele while megaphylls refer to a type of leaf with several or many large veins branching apart or running parallel and connected by a network of smaller veins.
What are the characteristics of microphylls?
The main characteristic feature of microphylls is the presence of a single vein, which is unbranched. Also, this single vein emerges from protostele without leaving a leaf gap.
What are some examples of megaphylls?
Generally, the leaves of angiosperms and gymnosperms and fronds of ferns are examples of megaphylls. However, some gymnosperms contain needle-like leaves with a single vein. Basically, these leaves are complex leaves derived from megaphylls.
Overview
The gymnosperms (pronunciation (help·info) lit. revealed seeds) are a group of seed-producing plants that includes conifers, cycads, Ginkgo, and gnetophytes, forming the clade Gymnospermae, the living members of which are also known as Acrogymnospermae. The term gymnosperm comes from the composite word in Greek: γυμνόσπερμος (γυμνός, gymnos, 'naked' and σπέρμα, sperma, 's…
Classification
A formal classification of the living gymnosperms is the "Acrogymnospermae", which form a monophyletic group within the spermatophytes. The wider "Gymnospermae" group includes extinct gymnosperms and is thought to be paraphyletic. The fossil record of gymnosperms includes many distinctive taxa that do not belong to the four modern groups, including seed-bearing trees that have a somewhat fern-like vegetative morphology (the so-called "seed ferns" or pteridosperms). …
Diversity and origin
Over 1000 living species of gymnosperm exist. It was previously widely accepted that the gymnosperms originated in the Late Carboniferous period, replacing the lycopsid rainforests of the tropical region, but more recent phylogenetic evidence indicates that they diverged from the ancestors of angiosperms during the Early Carboniferous. The radiation of gymnosperms du…
Uses
Gymnosperms have major economic uses. Pine, fir, spruce, and cedar are all examples of conifers that are used for lumber, paper production, and resin. Some other common uses for gymnosperms are soap, varnish, nail polish, food, gum, and perfumes.
Life cycle
Gymnosperms, like all vascular plants, have a sporophyte-dominant life cycle, which means they spend most of their life cycle with diploid cells, while the gametophyte (gamete-bearing phase) is relatively short-lived. Like all seed plants, they are heterosporous, having two spore types, microspores (male) and megaspores (female) that are typically produced in pollen cones or ovulate co…
Genetics
The first published sequenced genome for any gymnosperm was the genome of Picea abies in 2013.
General bibliography
• Cantino, Philip D.; Doyle, James A.; Graham, Sean W.; Judd, Walter S.; Olmstead, Richard G.; Soltis, Douglas E.; Soltis, Pamela S.; Donoghue, Michael J. (August 2007). "Towards a phylogenetic nomenclature of Tracheophyta". Taxon. 56 (3): 822–846. doi:10.2307/25065864. JSTOR 25065864.
External links
• Gymnosperm Database
• Gymnosperms on the Tree of Life
• Albert Seward (1911). "Gymnosperms" . Encyclopædia Britannica (11th ed.).