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Phycokey
Morphology |
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Organization
within Phycokey is based on separation of morphological features easily
recognizable in a student-grade microscope.
The first level of separation is generally the most apparent: unicells (single cells), colonies, and
filaments. Second,
where useful, unicells are separated on the basis of flagellated and
non-flagellated. In other cases the presence
or absence of an extracellular gelatinous sheath is useful. Filamentous
forms are separated into branched and unbranched, tapered or untapered, cell
differentiation or not, sheath present (‘filaments’) or no sheath (‘trichomes’),
and other attributes where applicable. Additional
characteristics useful in various groups include chloroplast characteristics
(shape and number per cell), spores, cell connections in colonies and
filaments. Diatoms are further separated based on raphes (biraphes and monoraphes) or lack thereof (araphes), symmetry and pores (punctae). Cyanobacteria
are separated further on the basis of presence or absence of nitrogen-fixing
heterocysts. Conjugate
greens (desmids and non-desmids) are separated from non-conjugate greens even
though this is not directly and explicitly through their morphology. In summary
the navigation via morphology in Phycokey is similar to that used in standard
dichotomous (bifurcate) keys, but with the added advantage, usually, of
comparing more than two images at any level of decision that leads to a
genus. |
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