The genus Abies is the fir genus of the conifers. It has single needle-like leaves with cones that stand erect on the branch.
(scouring rushes)
Abscission is the orderly process by which a leaf dies and falls off the tree or a fruit ripens and falls from a plant.
An acorn is a fruit with a bony pericarp, classified as a nut. It produces a cupule in which the fruit sits. Acorns are only the genus Quercus and Lithocarpus in the family Fagaceae, a dicot in the division Anthophyta.
DIAGRAM: Acorn Seed Structure
PHOTO:
Adjacent is a term that refers to the proximity of two objects. It means that the two objects are right next to each other or beside each other.
Adventitious buds form along a stem, generally after the stem has had an injury. This is a survival response for the plant. These adventitious buds will differentiate either into roots or shoots depending upon whether they are above or below ground. This is what allows gardners to plant a cutting of a stem and it will grow up into a mature plant.
DIAGRAMS: Equisetum Stem
PHOTOS:
DIAGRAMS:
PHOTO: Aeciospores
DIAGRAMS:
PHOTO: Aecium
Aerenchyma are parenchyma cells that are associated with an air space or surround open canals as in the air space of a monocot vascular bundle or the vallecular or carinal canal of a horsetail.
DIAGRAM: Tissue Types
PHOTOS:
(bromileads)
Air chambers generally refers to the open chambers in the thallus of Marchantia and other liverworts. This is a chamber in the upper portion of the thallus that has a pore at the top so that gas exchange can occur between the leaf and the open air outside the thallus.
DIAGRAM: Leaf Cross-section / Monocot Vascular Bundle
PHOTOS:
DIAGRAMS:
PHOTOS: Akinetes 1 / Akinetes 2
Algae are single-celled to many-celled organisms that contain various photosynthetic pigments and belong to the Division Protista. They can be single-celled to clusters of cells called colonies to filaments of cells (cells hooked end to end). The algae that most people see is usually green in color because of the chlorophyll their cells contain.
Alternate refers to the arrangement of either buds or leaves along the stem. Alternate budding or leaves is one bud or leaf per node.
DIAGRAM: Alternate Leaves
PHOTO:
(ribbing and furrowing)
(capsule example)
An ament is a spike of unisexual flowers that is typically pendulous but in some species it is erect. Aments are also known as catkins.
DIAGRAM: Ament Inflorescence
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DIAGRAMS:
PHOTOS: Amphithecium
The term anatomy refers to the internal structure of any biological entity. Plant anatomy studies the internal parts of the stem like the xylem, phloem, annual rings, fibers, etc. In animals, it is a study of their internal organs such as the stomach, liver, large intestine, gall bladder, etc.
DIAGRAM: Wind Pollinators
PHOTOS:
Annual rings are the layers of wood laid down by the vascular cambium in a woody dicot or a gymnosperm. Because the vascular cambium is active in the spring through the fall, xylem cells are being added to the circumference of the xylem tissue. In the spring these cells grow fast and are large, however as the summer progresses into fall, the numbers of cells being produced slows down and finally stops. At the same time, the cells get smaller and smaller. The next spring when the vascular cambium breaks dormancy, the cells are large and fast-growing again. Thus, the difference in size between the small cells (summer wood) and the new spring cells (spring wood) forms a line between the spring and summer wood. This then marks the boundary of an annual ring.
DIAGRAMS:
PHOTOS: Annual Rings
DIAGRAM: Annual Growth Cycles
PHOTOS:
Annular is a term that describes the secondary wall thickening pattern in vessels. Annular thickening are a hoop of secondary wall that circles the vessel. Typically several annular hoops, which do not touch one another, of secondary tissue will be found along the length of a vessel.
(ferns and moss capsule)
DIAGRAMS:
PHOTOS: Fern Sporangium
DIAGRAM:
The plural form of antheridium.
The umbrella-like structure that contains antheridia growing attached to the upper surface of the thallus of Marchantia and other members of the liverworts.
DIAGRAM:
PHOTO: Marchantia / Marchantia
DIAGRAM:
This is the stalk upon which the antheridial disc stands.
DIAGRAM:
PHOTO: Marchantia
The male gametangium where the sperm is produced and housed.
DIAGRAM:
Marchantia / Marchantia / Marchantia
DIAGRAM:
PHOTO:
Anthoceros
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Anthoceros
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Anthoceros
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Anthoceros
Anthoceros
The aperture is the opening in something. If the aperture is larger, then the opening into structure is larger, and if the aperture is smaller, then the opening into the structure is smaller. For example, the aperture of guard cell pore is at its maximum during the middle of the day.
The apex it the upper tip end of a stem or leaf. The apex of a stem is at the point of the terminal bud. The apex of a leaf is at the tip end opposite the petiole.
Buds that produce stems and that are located at the tip of the stem.
DIAGRAM:
PHOTOS:
The apical cell is the cell at the end of the filament on Oscillatoria that is convex because of the turgor pressure that causes it bulge a bit on one side.
DIAGRAM:
PHOTO: Apical Cell
Meristem is embryonic tissue. Apical meristem is meristem at the tip of the stem. Thus, apical meristem is meristem tissue that is contained in the terminal or apical buds.
DIAGRAM: Root Anatomy
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DIAGRAM:
DIAGRAM:
PHOTO: Marchantia / Marchantia / Marchantia / Marchantia
DIAGRAM:
PHOTO: Marchantia / Marchantia / Marchantia / Marchantia
DIAGRAM:
PHOTO: Marchantia / Moss / Fern 1 / Fern 2
DIAGRAM:
PHOTO: Moss Capsule
DIAGRAM: Head Inflorescence
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The auricles are to small small fingers of tissue at the base of the leaf blade of a grass that extend partially around the grass stem.
DIAGRAM:
PHOTOS:
(autoclaved herring sperm)
The axial system is the vascular transport system in a stem that runs vertically (up and down). This is in contrast to the lateral system that runs right and left, or out two the margin of the stem. The axial system carries water and raw minerals up the stem in the xylem and it carries glucose in the phloem up and down the stem. The axial system is composed of fibers for strength, sieve-tube members and companion cells in the phloem and fibers, vessels and tracheids in the xylem. The fusiform initials are what produces the axial system.
The axil is the angle between the petiole of a leaf and the stem. It is not uncommon to find branch buds in the axil of a leaf.
DIAGRAM: Leaf Axil
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