Field of Science

Showing posts with label nucleus. Show all posts
Showing posts with label nucleus. Show all posts

Friday Fabulous Flower - spiderwort


Various species and cultivars of the genus Tradescantia (spiderworts) make very nice additions to your perennial garden and naturalized gardens, although they can be a bit weedy, so dead heading is a good idea. The flowers are fairly large, 1" diam, and blue to purple (like in the image); some cultivars are lighter, almost white, or more purple.  They all have the sort of hairy looking center of the flower (the spider?).  These are long filamentous hairs (trichomes) on the stamen filaments.  Under a microscope the cells composing the hairs look rather like beads.  They are mostly filled with a central vacuole, a water-filled sac that contains a purple pigment.  The other cytoplasmic contents of the cells a pushed out against the cell wall occupying the ends of the cell with strands running along the cell wall.  The large blobby sac is the cell's nucleus. According to biological history it was in exactly such spiderwort filament hair cells  that Robert Brown, he of Brownian motion, first observed the nucleus of a cell (1833). It's a great specimen to observe the streaming of cytoplasm too.

Friday Fabulous Flower - Spiderwort

Friday, June Oneth, and it was in the 40s this AM, so the fingers on the handle bars got really cold while riding in.  But gloves?  In June?  And the house heat on too?  This isn't Wisconsin or Maine!  So May brought us record high temperatures, and temperatures so low the heat came on, just about a 40 degree F range of daily highs.  May brought us a lot of June flowers pushed along by the early spring.  One of the Phactor's favorite plants is now flowering, here and there throughout our gardens, spiderworts, members of the genus Tradescantia.  As to species, who knows?  Many seem to be hybrids with T. virginiana as a parent.  Several familiar house plants (Zebrina, Rhoeo) formerly placed in different genera are now treated as species of Tradescantia.  Notice the little hairs on the stamen filaments.  These trichomes look like strings of snap beads (remember snap beads?), and it you have a microscope they are well worth the look both because they are pretty and because historically these are the cells in which a nucleus was observed by Robert Brown (1773-1858), and while nuclei were observed earlier by von Leeuwenhoek, it was Brown who called them the cell nucleus, and although based on a misunderstanding of how it functioned in cell biology, the term stuck.  Curiously he thought that perhaps the nucleus was a feature unique to the cells of monocots.  The trichome cells are also a great place to observe cytoplasmic streaming which is why species of Tradescantia are kept in our glasshouse.  Lastly, for reasons unknown to the Phactor, the flower color we perceive is never the flower color recorded by either film or digital cameras.  Perhaps some refraction is involved.