Guide to Hornworts of Oregon: Anthoceros punctatus L.
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Hornworts 1b stalked ventral tubers absent > Hornworts 2a spores black > Anthoceros 1b spores smooth on proximal face > Anthoceros punctatus
Anthoceros punctatus L.
Special status: None
Recognition: Solitary chloroplasts in young epidermal cells characterize the family; black spores and a lamellate thallus with internal mucilage chambers characterize the genus. Examination of spores at high magnification is necessary to confirm species identification: this species has a smoothly foveolate surface filling the proximal faces of the spores contrasting with the strong ornamentation in A. fusiformis. The spines on the spores of A. punctatus are stouter and often appear forked in tangential view, while in A. fusiformis the spines are sharper and more distinct.
Distribution: On soil, usually recently disturbed, most often in urban areas. Not common away from towns. Representative specimens: Curry Co.: Harris Beach Wayside, Wagner 1987 (ORE); Lane County, Sutton Beach, Wagner m1758 (DHW).
Comments: I believe that this species is possibly exotic, introduced into the area. It often forms huge colonies on recently prepared landscape beds, these colonies most vigorous in the first year or two and then declining. As often as not, a fresh layer of bark-o-mulch is the cause of a colony's demise.
Doyle has found the closely related Anthoceros agrestis Paton in coastal California. This has antheridia less than 100 μm long compared with longer antheridia in Anthoceros punctatus (Doyle & Stotler 2006). The population from Sutton Beach whose antheridia were examined proved to be ordinary Anthoceros punctatus.
Anthoceros punctatus. Spores, lower two in proximal view, upper four in distal view. Sutton Creek, Lane Co., Oregon. DHW m1758
SEM spore images: distal, proximal and side views. Calif., Humboldt Co., Centerville Road southwest of Ferndale. Doyle 11379 (UC); © W.T. Doyle June 2007. Used with permission.
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