Chondracanthus exasperatus morphology
So you've seen a couple pictures by now, but what is C. exasperata really like physically?
BLADE STIPE HOLDFAST
Cell Wall: The microfibrillar framework of C. exasperatus' cell wall is made of cellulose. The bulk of the cell wall, however, is made of mucilage, specifically carrageenans .
Chloroplasts: Chloroplasts are discoid in shape and have no endoplasmic recticulum. There is one thylakoid per band. The major pigments are chlorophyll a and d, and the accessory pigments include phycobilins, carotenoids, and phycobiliproteins.
Storage products: The major storage products is floridean starch which is maintained in the cytoplasm.
Pit Connections: Pit
connections are unique cell connections found in almost all red algae. They
form at cell junctions when apical cells divide to form the filaments of
the red alga thallus. Pit connections can be defined as the opening
in the cell wall between two cells which is filled in by a plug and plug
cap. They can form either during cell division, primary pit
connections, or between two cells which come to lie near each other, secondary
pit connections. The diagram shows the formation of a primary
pit connection. After the nucleus divides during cell division, the
cross wall begins to grow inwards (a), but stops before it completely closes
the opening between the two cells (b). Parallel vesicles line up in
this aperture (c) and attract electron-dense material to the opening. This
electron-dense material is surrounded by a membrane to form the "plug" and
stabilized on either side by a flattened vesicle, or "plug cap" (d). Their
name is misleading because there really is no connection between the two
cells. Instead, it is hypothesized that pit connections increase the
stability of the thallus (Lee, 1980).
Resorcinol method: The resorcinol
method has been used with success to identify the nonreproductive gametophyte
and sporophyte stages of isomorphic red algae. The procedure
involves applying the resorcinol reagent, composed of resorcinol, acetal
and HCl, to sections of the blade of a red alga whose life history phase
is unknown. If the reagents remains clear, the section is from a sporophyte,
however if it turns red this indicates the section is from a gametophyte. This
test depends on the different amounts and types of carageenan found in the
different life history phases of many reds. In gametophytes,
there is typically kappa-carageenan, which reacts with resorcinol to turn
it red, whereas sporophytes have primarily lamba-carageenan, which
does not react with resorcinol.
Papillae: While the morphology of the papillae is not useful in identifying nonreproductive life history phases in C. exasperatus, they can be used to identify reproductive phases. No studies have been done on how reliable this method is at identifying life history phases, however there are noticeable macroscopic morphological differences between the papillae in male gametophytes, female gametophytes, and sporophytes.
While these distinctions are useful, my investigations of general Chondracanthus papillae found that they were extremely variable among species and thus it was hard to establish an easy set of identifying criteria. Some examples of the extreme variety in papillae among Chondracanthus are given below, along with whether or not they contained reproductive cystocarps in their papillae.
1) large view
part 1 part 2
papillae without cystocarp papillae with cystocarp
3) large view papillae