Dioecious

Dioecious [ Biology - Botany ]

Dictionary of botanic terminology - index of names

Varieties or species having staminate (male) flowers and pistillate (female) flowers on separate plants

Dioecious translates from Latin to mean, "two houses".

Euphorbia obesa
Pistillate (female) specimen
with fruit.

Euphorbia obesa
Staminate (male) specimen
with pollen.

In biology a dioecious organism is male or female, and reproduces via sexual reproduction, being therefore the opposite of a hermaphrodite. Hence dioecious organisms produce only one type of gamete;

In botany the term dioecious describe a plant populations with unisexual (not perfect) flowers, with reproductive structures upon distinct individuals, male and female organs do not co-occur in the same plant.
Therefore, a pollinating male plant bears no fruits or seeds, whereas a female plant may have fruits and seeds. This plants must be cross pollinated; consequently a female plant will only bear fruit when a male grows nearby, and male plants do not bear fruit. For fruit or seeds production it is indispensable the presence of both plants sexes. But usually only one male plant is needed to pollinate several female plants.

Approximately 3-4 percent of all flowering plants are dioecious. Although dioecism favours cross pollination, there is a reduced seed production because only half of the population (the female plants) bear seeds.

This term is sometime incorrectly applied to individual flowers.

For example Euphorbia obesa.

Compare with: Monoecious.

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Holdfast roots [ Botany ]
Dictionary of botanic terminology - index of names

Some species of climbing plants develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place.

Climbing plants, like the poison ivy (Toxicodendron radicans), Boston ivy (Parthenocissus tricuspidata), and trumpet creeper (Campsis radicans), develop holdfast roots which help to support the vines on trees, walls, and rocks. By forcing their way into minute pores and crevices, they hold the plant firmly in place. Usually the Holdfast roots die at the end of the first season, but in some species they are perennial. In the tropics some of the large climbing plants have hold-fast roots by which they attach themselves, and long, cord-like roots that extend downward through the air and may lengthen and branch for several years until they strike the soil and become absorbent roots.

Major references and further lectures:
1) E. N. Transeau “General Botany” Discovery Publishing House, 1994