acotyledon (s) (noun)
, acotyledons (pl)
Any plant without seed leaves: The new plant in the garden was just beginning to sprout and had not yet developed acotyledons or new leaves.
Having no seed lobes, as applied to plants which have no true seeds; such as, ferns, mosses, etc. One primary example is the dodder, a leafless parasitical vine with yellowish threadlike stems. It attaches itself to some other plant; such as, flax, goldenrod, etc, Is nourished by the plant that supports it.
A cuplike cavity or organ. Same as acetabulum (anatomy, the cup-shaped cavity at the base of the hipbone into which the ball-shaped head of the femur fits; or in zoology, the cavity in the body of an insect into which the leg fits).
cotyledon, cotyledonary, cotyledonal
1. The first leaf or leaves in the embryo of flowering plants and other seed plants.
2. One of the first leaves to appear after germination (there may be one, two, or more); the foliar portion of the embryo as found in the seed.
Shaped like a cotyle or a cup.
1. Shaped like a cup; as, the cotyloid cavity, which receives the head of the thigh bone.
2. Pertaining to a cotyloid cavity; such as, the cotyloid ligament, or notch.
Stem lizards that evolved from amphibians during the Early Carboniferous period. and went extinct at the end of the Triassic period.
An order of primitive reptiles descended from certain labyrinthodont amphibians. The cotylosaurs were probably the stem reptiles, from which other reptilian orders evolved.
A flowering plant with two embryonic seed leaves or cotyledons that usually appear at germination and whose subsequent leaves have a network of veins. Most herbaceous plants, trees, and bushes are dicotyledons.
Consisting of seed plants that produce an embryo with paired cotyledons and net-veined leaves; divided into six (not always well distinguished) subclasses (or superorders): Magnoliidae and Hamamelidae (considered primitive); Caryophyllidae (an early and distinctive offshoot); and three more or less advanced groups: Dilleniidae; Rosidae; Asteridae [synonyms: Dicotyledones, class Dicotyledones, Dicotyledonae, class Dicotyledonae, Magnoliopsida, class Magnoliopsida].
1. The stem of a seedling between the cotyledons and the first true leaves.
2. That part of the stem above the cotyledons.
hectocotylus (s); hectocotyli (pl)
A modified arm of the male of certain cephalopods, such as the octopus, functioning as a reproductive organ in the transference of sperm to the mantle cavity of the female. It is a specialized, extended tentacle used to store spermatophores, the male gamete. Males generally form a new hectocotylus in each new season.
The part of the stem of an embryo, or young seedling, below the cotyledons.
As the plant embryo grows at germination, it sends out a shoot called a radicle that becomes the primary root and penetrates down into the soil. After emergence of the radicle, the hypocotyl emerges and lifts the growing tip (usually including the seed coat) above the ground, bearing the embryonc leaves (called cotyledons) and the plumule that gives rise to the first true leaves.
The hypocotyle is the primary organ of extension of the young plant and develops into the stem.
A plant with one cotyledon or seed leaf. A very important group of flowering plants, dominating great parts of the earth and with many economically important plants.
The largest monocot family is the Orchidaceae (orchids), with very complex (and striking) flowers, for highly specific insect pollination.
The second largest and perhaps more notable family, the Poaceae or Gramineae (true grasses), have evolved in another direction, becoming highly specialized for wind pollination. Grasses produce small flowers, which may be gathered in highly visible plumes; such as, inflorescences.
Comprising seed plants that produce an embryo with a single cotyledon and parallel-veined leaves. Includes grasses and lilies and palms and orchids; divided into four subclasses or superorders: Alismatidae; Arecidae; Commelinidae; and Liliidae [synonyms: Monocotyledones, class Monocotyledones, Monocotyledonae, class Monocotyledonae, Liliopsida, class Liliopsida].