Angiosperms

Angiosperms - Chinese Bladdernut Buds

The name "angiosperms" has long been used by botanists to refer to the flowering plants, a group of approximately 235,000 species. All angiosperms are members of the phylum Anthophyta.

The name "angiosperm" is actually derived from two Greekwords, angeion,meaning "vessel" or "container", and sperma, meaning "seed". The name was given in reference to the fact that the seeds of all flowering plants develop from ovules that are enclosed in a structure called a carpel.

This characteristic sets the angiosperms apart from all other plants, which either do not have seeds or have seeds that are not developed in structures resembling a carpel. Although the name angiosperm is used widely, plant taxonomists and many botanists typically refer to them by the more formal name Anthophyta, the phylum that contains the flowering plants.

Archaea

Archaea

The domain Archaea represents a diverse group of prokaryotes originally found in environments once considered to be hostile to life, now known to be widely distributed in nature.

The cycling of plant nutrients, such as carbon, nitrogen, and sulfur, requires the activity of microorganisms that convert these elements to forms readily available to plants. These microorganisms, which are generally found in both soil and water, include both prokaryotic organisms of the domain Bacteria and the domain of prokaryotes called Archaea, which play significant roles in nutrient cycling.

Along with Eukarya, to which protists, fungi, plants, and animals belong, the Archaea formone of the three domains of life. The Archaea are related to both Bacteria and Eukarya and, in some respects, appear to bemore closely related to Eukarya.

Ascomycetes

Ascomycetes

The ascomycetes are fungi (phylum Ascomycota or Ascomycotina) that produce sexual spores in a specialized cell called an ascus. These diverse fungi, with more than thirty thousand species, can be found in almost every ecosystem worldwide. One of the most famous members of the ascomycetes is the truffle.

Ascomycetes, one of the four phyla of the fungus kingdom, by definition possess an ascus, a single cell inside of which sexual spores are produced.

The reproductive process has been well documented and occurs when the dikaryotic mycelium (the mass of hyphae forming the body) undergoes changes that precede the formation of the ascus. Dikaryotic is the genetic state in which two haploid nuclei are present in the cell. One nucleus is donated by each parent.

Basidiomycetes

Flammulina velutipes is example of Basiodiomycetes

The Basidiomycetes constitute the largest of the three classes of the Basidiomycota (basidiosporic fungi), a very large class of about fourteen thousand species of the most diverse terrestrial fungi.

The largest fungi belong in the Basidiomycetes class, as do some of the most unusual. All members of Basidiomycetes produce a basidium from hyphal cells and not from spores. (The basidiumis a cell produced at the end of a dikaryotic hypha.)

The basidium will produce either two or four spores as the result of meiosis. The basidium may be either a nonseptate cell, with two or four sterigmata (the basidiospore is produced on the end of the sterigma) at the apex, or it may be septate.

Basidioporic Fungi

Basidioporic Fungi

Basidiosporic fungi (also known as the Basidiomycota or Basidiomycotina) are fungi that produce sexual spores on a specialized cell called a basidium.

The basidiosporic fungi are the most diverse phylum of the fungi world, with more than 22,300 species described. Some of the fungi in this phylum are microscopic, while the larger members of this group produce fruiting structures that are basketball-sized and weigh in excess of 10 pounds.

This phylum contains fungi that fall into three classes: mushroom, rusts, and smuts—and range widely in appearance, from the common mushroom to weblike fungi with an odor that can be detected at several feet.

Bromeliaceae

Bromeliaceae

The family Bromeliaceae comprises a group of perennial, monocotyledon herbs or trees that often age slowly.

Important ornamentals (called bromeliads) as well as sources of food and medicines, Bromeliaceae have substantial economic value and are widely cultivated. The colors of the leaves offer decorative foliage, and the flowers are of astonishing hues due to the rich content of pigment-forming substances known as anthocyanins.

Based on ovary position, habit, and floral and pollen morphology, the family Bromeliaceae has been split into three subfamilies: subfamily Pitcairnioideae, subfamily Tillandsioideae, and subfamily Bromelioideae.

Brown Algae

Brown Algae

Seaweeds that are brown to olive-green in color belong to the phylum Phaeophyta, or brown algae, which includes between fifteen hundred and two thousand species.

Brown algae (phylum Phaeophyta) are familiar to most people as brown or dark green seaweeds. Some brown algae are microscopic in size, but many are relatively large: One giant kelp measured 710 feet in length. All brown algae are multicellular.

Appearance and Distribution

Brown algae have a body, called a thallus, which is a fairly simple, undifferentiated structure. Some thalli consist of simple branched filaments. Some brown algae have more complex structures called pseudoparenchyma because they superficially resemble the more complex tissues of higher plants.

Bryophytes

Bryophytes

Bryophytes comprise three phyla of nonvascular plants, which generally lack the specialized conductive tissues (xylem and phloem) that are found in the vascular plants, are small in size, and are distributed worldwide in moist, shady habitats.

Bryophytes (from the Greek word bryon, meaning “moss”) were once grouped together into one large phylum. Many botanists today recognize that these organisms belong to at least three distinct phyla: phylum Hepatophyta (the liverworts), phylum Anthocerophyta (the hornworts), and phylum Bryophyta (the mosses).

Origin and Relationships

Bryophytes are thought to have originated more than 430 million years ago, during the Silurian period. Many botanists speculate that bryophytes arose from an ancestor in the green algal order Charales or Coleochaetales based on biochemical, morphological, and life history comparisons.

Cellular Slime Molds

Cellular slime molds, or dictyostelids, were originally considered to be fungi. These microscopic, multicellular organisms are easily mistaken for some of the microfungi that commonly occur as contaminants in laboratory cultures. However, cellular slime molds are more closely related to the protozoans than to fungi.

Although once thought to be fungi, the protists of the phylum Dictyosteliomycota actually have more in common with the paramecium or amoeba that can be observed in a drop of pond water when viewed under the microscope than they do with mushrooms and toadstools.

Cellular slime molds are essentially microscopic throughout their entire life cycle, and only rarely can they be observed directly in nature, as is the case for the plasmodial slime molds. Cellular slime molds must therefore be grown under controlled laboratory conditions in order to be studied.

Charophyceae

Spirogyra

It is almost impossible not to see Spirogyra floating on the surface of a pond on a hot summer day, but most people dismiss it as pond scum. Few realize that what they are looking at is a member of the Charophyceae, a class in the phylum Chlorophyta, or green algae, and a cousin of the ancestor of the Embryophyta, or bryophytes and vascular plants.

Most Charophyceae, like Spirogyra, live in freshwater habitats, but some also occur in moist soil in terrestrial habitats. Charophyceae can live as single cells, colonies, or branched and unbranched filaments and come in a variety of shapes.

The characteristics that unite members of the class—and which link them with the embryophytes—include flagellated cells (similar to sperm cells in vascular plants), a nuclear envelope that breaks down during mitosis, mitotic spindles that persist as phragmoplasts (a type of cytoskeletal scaffolding) through cell division either by furrowing or by forming a cell plate, the presence of chlorophylls a and b and phytochrome, and the storage of starch inside plastids.

Chlorophyceae

Chlorophyceae (from the Greek word chloros, meaning “green”) make up an extremely large and important class of green algae. Members may be unicellular, colonial, or filamentous. Cells of unicellular and colonial chlorophyceans may have two or more flagella.

There are about 2,650 living species of chlorophyceans. The main features of the class (and most plants) are the use of starch as the principal food reserve and the green chloroplasts with chlorophylls a and b. In spite of plant characteristics, this algal group is not directly related to early land plants.

Chlorophyceans are almost entirely restricted to freshwater and terrestrial habitats. Some members of this class have adapted to life on snow as snow algae. Snow algae cause snow to appear red-burgundy or orange in color because of high levels of unusual carotenoid pigments within the algal cells.

Chrysophytes

The Chrysophyceae, classified within the kingdom Chromista, are mostly unicellular or colonial organisms found in fresh and salt water throughout the world.

The Chrysophyceae (in some systems corresponding to the phylum Chrysophyta) are related to heterokont algae and include more than eight hundred described species that are classified in approximately one hundred genera.

They aremost closely related to the Synurophyceae and other pigmented heterokont algae, including the Bacillariophyceae (diatoms), Eustigmatophyceae, Phaeophyceae (brown algae), and Xanthophyceae (yellow-green algae), among others.

Chytrids

Chytrids

Chytrids are fungi in the phylum Chytridiomycota. They have motile spores and are primarily aquatic organisms.

Like all fungi, chytrids live in their food and have an absorptive mode of nutrition in which they secrete digestive enzymes and absorb the breakdown products.

Chytrids also have cell walls made of chitin, make the amino acid lysine via the amino adipic acid (AAA) pathway, and possess a ribosomal DNA (deoxyribonucleic acid) sequence that places them more closely with other fungi than with any other group of organisms. The feature that sets the mapart from other fungi is the possession of a motile zoospore. All other fungi produce spores without flagella.

Characteristics

Aposteriorly oriented, whiplash-type flagellum is the feature that unites all the organisms in the division Chytridiomycota within the kingdom Fungi. As absorptive heterotrophs, they live either as saprophytes, growing on dead organic matter, or as parasites in living plants, other fungi, insects, or algae.

Compositae

Compositae

In number of species, the family Compositae or Asteraceae, commonly known as the sunflower family, is among the largest families of flowering plants.

The Compositae family consists of more than eleven hundred genera worldwide and possibly as many as twenty-three thousand species. Representatives of the family are found on every continent except Antarctica.

Species diversity is high in the southwestern United States and Mexico, in southern Brazil and along the South American Andes Mountain range, along the Mediterranean region, in Southwest and Central Asia, in South Africa, and in Australia.

Cryptomonads

Cryptomonads

The phylum Cryptophyta describes tiny, motile, unicellular organisms with two slightly unequal flagella bearing lateral hairs. Cryptomonads live mainly in marine and freshwater environments.

Some cryptomonads are alga-like, with bluegreen, red, and olive-brown photosynthetic pigments including chlorophylls a, c2, alpha-carotene, xanthophylls (alloxanthin, crocoxanthin, zeaxanthin, and monadoxanthin), and phycobiliproteins (phycoerythrin and phycocyanin).

Cryptomonads are found in a variety of moist places, such as algal blooms in the ocean or in fresh water, and on beaches. Some members are intestinal parasites in animals.

Deuteromycetes

Deuteromycetes

Deuteromycetes are an artificial group of fungi, of which there exist approximately fifteen thousand species, often referred to as “fungi imperfecti” because their only known reproductive mechanism is asexual.

Deuteromycetes—also known as Deuteromycota, Deuteromycotina, fungi imperfecti, and mitosporic fungi—are fungi that are unable to produce sexual spores and are therefore placed in their own separate phylum. The deuteromycetes are commonly called fungi imperfecti, that is, “imperfect fungi,” a term accepted by many mycologists.

Reproduction

Reproduction in the deuteromycetes occurs in several different forms. Spores, or conidia, may be produced directly on the mycelium (the mass of hyphae, or tubular filaments, forming the body of a fungus) or on a structure of specialized mycelial cell called a condiophore.

Diatoms

Diatoms

Diatoms are unicellular microorganisms of the phylum Bacillariophyta that are abundant in aquatic, semi aquatic, and moist habitats throughout the world, growing as solitary cells, chains of cells, or members of colonies.

Diatoms, algal organisms of the phylum Bacillariophyta, have more than 250 genera and about 100,000 species. A distinctive siliceous cell wall called a frustule surrounds each vegetative cell. Diatoms have an extensive fossil record, going back some 100 million years to the Cretaceous period.

Deposits of fossil diatoms, known as diatomite or diatomaceous earth, are mined commercially for use as abrasives and filtering aids. One subterranean marine deposit in Santa Maria, California, is about 900 meters in thickness. More than 270,000 metric tons of diatomaceous earth are quarried annually from a deposit in Lompoc, California.

Dinoflagellates

Dinoflagellates

Dinoflagellates, phylumDinophyta, are unicellular and colonial algal organisms from the kingdom Protista named for the spinning motions that result from the movement of their flagella.

The two thousand to four thousand species that make up the Dinophyta phylum typically have two flagella. Dinokonts (Dinophyceae) have one flagellum running in a groove that cuts transversely across the cell and another flagellum, the sulcus, that runs backward in a longitudinal groove and is more or less perpendicular to the transverse one. In desmokonts (Desmophyceae), both flagella arise from a point at the front of the cell.

The motions of the flagella, which make dinoflagellates spin like a top, help give rise to the name, for dinos in Greek means “whirling,” and flagella means “whip.” Single-celled species are the most common, but colonial species exist. The largest dinoflagellate, Noctiluca, may grow as large as 2 millimeters in diameter.

Eudicots

Eudicots

The eudicots, class Eudicotyledones (literally “true dicots”), are descended from a common ancestor and comprise three-quarters of all flowering plants. It is one of the two main classes of the angiosperms, the other being the monocots, or Monocotyledones.

Eudicots, the common name used for class Eudicotyledones, are the most common group of flowering plants, comprising 75 percent of all angiosperms. The other 25 percent, monocots (Monocotyledones), are often characterized by pollen grains that have a single aperture (or line of weakness).

Eudicots have pollen grains that typically possess three apertures, referred to as triaperturate pollen. Thus, there is no monocot-dicot division among the flowering plants.

Euglenoids

Euglenoids

Organisms called euglenoids, the algal phylum Euglenophyta in the kingdom Protista, make up a large group of common microorganisms numbering between 750 and 900 known species.

Euglenoids can be found in both fresh and stagnant water. Some genera of euglenoids can also be found in marine habitats. Euglena and Phacus are representative common genera. Euglenoids are unicellular, except for those of the colonial genus Colacium.

Because euglenoids have flexible cell coverings, move about freely, and ingest their food through a structure called a gullet, many scientists have classified the euglenoids as animals. Some species of euglenoids, however, have chloroplasts and are able to supply at least some of their food needs through photosynthesis.