Specimen #4: Gymnostomum aeruginosum

Collection #: 4

Scientific Name: Gymnostomum aeruginosum

Phylum: Bryophyta; Bryopsida

Order: Pottiales

Family: Pottiaceae

Common Name: toothless cup moss

Location: Chargin Falls area, OH

Habitat: On the stone by the side of the trail

Date of collecting: September 17th

Collector: Cornelia

Notes: extremely small species

How did I key this out:

 Fig.1 Group picture

Fig.2 Single plant (with and without capsule) with measurement

Fig.3 Single plants with capsules under a scope

Fig.4 Single leaf under a dissecting scope

From the picture of the group of the plant sample (Fig.1) and individual plants (Fig.2 & Fig.3), we could easily figure that this plant is in the acrocarp growth form. The leaf picture (Fig.4 and Fig.5) shows that this specimen is with lance-shaped leaves with a midrib (Fig.5 if you look closely and carefully enough). By knowing these features, we could now go to the key: KEY II: Acrocarps with Lance-shaped Leaves.

Fig.5 Single leaf under a microscope

The following steps is how I went through the keys:
1. (B) Plants darker green, yellow green, or brownish black, shoots loosely associated or if densely packed then not in domed mounds; leaves flat or folded but not tubular, with midrib usually visible at least at base of leaf. (See Fig.1, Fig.2 and Fig.5 for this fact.) (3)
3. (B) Plants on soil, rocks, trees, or logs in dry areas, or if in wetter areas, not submerged in water; leaves not folded at base. (4)
4. (B) Leaf surface not rippled or wavy when wet. (See Fig.4 and Fig.5 for this fact.) (9)
9. (B) Leaves <4 mm long. (21)
21. (B) Leaves spreading in various directions or barely diverging from stem when wet; plants lacking brood branchlets. (See Fig.3 and Fig.6 for this fact.) (22)
22. (B) Plants 0.2-2 cm tall. (See Fig.2 for this fact.) (34)
34. (B) Plants growing on rock, soil, rotting wood, tree base, or other substrate. (39)
39. (B) Shoot not surrounded by persistent protonema (no green film); leaves various. (See Fig.6 for this fact.) (40)
40. (B) Leaves not at all bluish and not cobwebby or moldy in appearance. (See Fig.4 for this fact.) (41)
41. (A) Leaves strongly contorted when dry, twisted and curled, sometimes into corkscrews. (See Fig.2 for this fact.) (42)
42. (B) Capsules upright, nor curved or grooved when dry. (See Fig.2 and Fig.3 for this fact.) (43)
43. (B) Capsules goblet- or egg-shaped (See Fig.3 and Fig.7 for this fact.), up to 1 mm long, stalks 2-8 mm tall. (See Fig.2 for this fact.) (45)
45. (B) Leaves 1-2 mm long. (46)
46. (A) Capsule rim lacking teeth. (See Fig.7 and Fig.8 for this fact.) (Gymnostomum aeruginosum, P83)

Fig.6 Branch under a scope

Fig.7 Capsule releasing spores

Fig.8 Capsule releasing spores in a closer view

 Fig.9 Spore cells in a closer look

Fig.10 Cell structure

Description of the species:
Plants prefer to grow on damp, calcium-enriched rock in shady spaces. Leaves are about 1 mm long. Capsules are goblet-shaped, toothless, and also usually lacking recessed, shallowly beaked lid.

Collecting and keying story:

On the day when I collected this, Willa told us to pay close attention to collect moss species with capsules, since sometimes it might be necessary to have a capsule while keying. As you can see from the pictures, this is a really small species and I almost missed the tiny capsules. But anyway I got it ^_^.
During the keying process, I picked out a single plant with the capsule on it and make a slide out of it to take a closer look of the capsule under the microscope to see whether it has teeth or not. Since I only keyed this one thing on that day, I just saved the slide for the next day to take a picture with other species.
On the second day, as soon as I put the slide under the scope, I saw Fig.7 happening. The cap was opened and the capsule was releasing spores!!! I got so excited that I actually screamed, and run all the way down the hall way to call Willa to come and see this fantastic fact. It was my first time to see real spores!!!
I took a huge bunch of pictures from different distances and got clear pictures of the spores. This is still a very exciting story for me to tell even until today.


Phylum, order and family name cited from:
http://plants.usda.gov/core/profile?symbol=GYAE

Keys cited from:

  Common Mosses of the Northeast and Appalachians by Karl B. McKnight, Joseph R. Rohrer, Kirsten McKnight Ward and Warren J. Perdrizet. This book is in the series of the Princeton Field Guides and was published by Princeton University Press with copyright @ 2013.