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PHYCOLOGICAL SOCIETY OF AMERICA

Botryoglossum

Morphology     Ecology     Life History     Taxonomy     Reproduction 

A Comparison

Botryoglossum - Cryptopleura

The physical characteristics that set B. farlowianum apart from various Cryptopleura are detailed below. Through my research, I found there to be a fairly obvious difference between the two genera. Because I am not a taxonomist, I am not quite sure if it is a species- or genus-level distinction, but I feel that B. farlowianum should continue to retain its status as a Botryoglossum.

The 1983 study done by Ver Steeg and Josselyn (see references) compared B. farlowianum, C. violacea, and C. lobulifera. 

One difference in the plants is the size. While they are fairly similar, B. farlowianum towers over C. lobulifera and is generally taller than C. violacea. In all the measurements done, B. farlowianum was found to be larger, although the range of sizes often overlapped. This caused the researchers to discount the difference to some extent, although the mean differences were always significant (P < 0.01 or more). 

So what's all this furor about? The history begins in 1843, with F.T. Kutzing's work, Phycologia generalis. In this volume, he erects the genera of Botryoglossum, though his specimen hails from South Africa. In 1872, J. Agardh, to whom credit is given for naming B. farlowianum, recognized seven species under this heading. Works by J.B. DeToni, in 1900, and H. Kylin, in 1924, transfer Agardh's designations into their current taxonomic positions. Much of the trouble with B. farlowianum may have arisen from the fact that, as Botryoglossum was originally identified in South Africa, matching of samples across such a geographical divide often is an unsure process.

The main controversy over B. farlowianum is its similarity to species of the genera Cryptopleura. 

Stipe midrib

    C. violacea

    B. farlowianum

 

As you can see, the stipe of C. violacea clearly lacks a distinct midrib vein, and is much broader than that of B. farlowianum. The two can also have midribs which look like the others in these pictures, but B. farlowianum always displays a midrib, and C. violacea generally does not.

Tetrasporangial sori

The study by Ver Steeg and Josselyn found that the sori which contain the tetraspores seem to be the main morphological difference between the two genera.  The sori of C. violacea are in marginal proliferations, and are linear along margins, not extending around the apices.

 

These dark rounded proliferations house the tetrasporangial sori of C. violacea.

 

 

The tetrasporangial sori of B. farlowianum also occur in the marginal proliferations, but these may extend onto the thallus from the margin. They are also found in rosettes on the thallus itself.  

And, in older plants, there are linear sori found over the division tips. 

These are the main ways that the two genera can be told apart. The linear sori on B. farlowianum's tip are actually distinguishable to the naked eye, so don't be discouraged in your beachside identification by your lack of a microscope. 

Edge appearance

The edges of the tips also tend to differ a bit between the two genera. 

The tips of Cryptopleura tend to be narrow, with one or multiple notches, while B. farlowianum's edges are broader, sometimes blunt or rounded, sometimes with notches that narrow off.

            

Here you can see the edge

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