from The American Heritage® Dictionary of the English Language, 4th Edition
- n. A mass of coherent pollen grains, found in the flowers of orchids and milkweeds.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A coherent mass of pollen, as in the milkweed and most orchids, which is dispersed as a single unit during pollination.
from the GNU version of the Collaborative International Dictionary of English
- n. A coherent mass of pollen, as in the milkweed and most orchids.
from The Century Dictionary and Cyclopedia
- n. In botany, an agglutinated mass or body of pollengrains, composed of all the grains of an anthercell.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. a coherent mass of pollen grains (as in orchids)
The pollen spores are usually aggregated into two or four waxy masses ( "pollinia," sing. pollinium), which usually can only be removed by the agency of insects upon which all but a very few orchids are absolutely dependent for the pollination of the flowers.
In this latter case we have a pollinium in its most highly developed and perfect condition.
A pollinium when highly developed consists of a mass of pollen-grains, affixed to an elastic footstalk or caudicle, and this to a little mass of extremely viscid matter.
Each pollinium consists of two leaves of pollen united for about half their length in the middle with elastic threads.
These I attempted to fertilise, but with two only of the six have I been successful: I succeeded in forcing a single pollen-mass into the stigmatic chamber of one of the latter, but I failed to do this on the other; however, by inserting a portion of a pedicel with a pollinium attached, I caused the latter to adhere, with a gentle press, to the mouth of the stigmatic chamber.
He who will carefully examine the flowers of orchids for himself will not deny the existence of the above series of gradationsfrom a mass of pollen-grains merely tied together by threads, with the stigma differing but little from that of an ordinary flower, to a highly complex pollinium, admirably adapted for transportal by insects; nor will he deny that all the gradations in the several species are admirably adapted in relation to the general structure of each flower for its fertilisation by different insects.