Well, I've managed to wrest Connor away from his exams for a bit. He's the author of today's write-up. Along with diving into today's write-up, I also suggest you visit Berry-Go-Round #4 at Foothills Fancies weblog. Berry-Go-Round is a weblog carnival devoted to plants.

Connor writes:

Many thanks to Michelle Fitterer for today's photograph.

Rhizomnium glabrescens is a moss that can easily be found in the Nitobe Memorial Garden. It forms a dense, shiny turf under the coverage of the garden's tiny forest. In Some Common Mosses of Birtish Columbia, W.B. Schofield reports that Rhizomium glabrescens is limited to western North America from California to Alaska and as far west as Montana.

The most striking features of this moss can be seen from this photograph. The leaves are a pale green colour with a pronounced costa, a central midrib of specialized cells. The costa is made up of a central conducting strand and thick-walled cells called stereids. The central conducting strand functions as a water transport and the stereids provide support for the leaf.

The leaf margin is also well differentiated. Marginal cells are elongate, lack chloroplasts, and are found in multiple layers (multistratose), while the rest of the leaf blade contains chloroplasts and is only one cell layer thick (unistratose). The UBC Biology 321 website provides excellent images of Rhizomnium glabrescens.

The male plants of Rhizomnium glabrescens possess a rosette of leaves making up the perigonial head. The dark cluster in the centre are many antheridia with paraphyses, sterile filaments of cells. Inside the antheridia, mobile sperm with flagellae are produced. The perigonial head acts as a splash cup, increasing the sperm's dispersal distance when a raindrop falls on it.