Panarctic Flora

342004-08 The Calamagrostis deschampsioides-lapponica-neglecta aggregate C. deschampsioides, C. holmii, C. inexpansa, C. lapponica, C. neglecta

Geography: Circumboreal-polar.

Notes: The reason for a common comment on this morphologically rather wide-spanning group is that some plants combine features suggesting a connection through allopolyploidy, and some taxa are proposed as propagating hybridogeneous species. At least one species of this collective group also hybridizes outside the group, C. neglecta with C. arundinacea (L.) Roth in the broad C. purpurascens affinity, with C. canescens (F.H. Wigg.) Roth in sect. Calamagrostis, and with C. epigejos in sect. Epigeios. However, there are no suggestions of allopolyploidy or any independent existence of these hybrids.

The number of species accepted in different accounts varies from three (C. deschampsioides, C. lapponica, C. neglecta) to at least ten (in addition, C. chordorrhiza, C. groenlandica, C. holmii, C. hyperborea, C. kolymaensis, C. inexpansa, C. sibirica, and some races). Tzvelev (PAF proposal and elsewhere) accepted eight species, two with two races: C. deschampsioides, C. neglecta subsp. neglecta and subsp. groenlandica, C. holmii, C. kolymaensis, C. chordorrhiza, C. inexpansa, C. hyperborea, and C. lapponica subsp. lapponica and subsp. sibirica. Eight of these taxa are reported from Eurasia, nine from North America including Greenland. We consider C. chordorrhiza and C. kolymaensis to be hybrids without independent existence (see below and Excluded taxa). Greene (1980, 1984) accepted three species, one with races, in the northern parts of North America: C. deschampsioides, C. lapponica, and C. stricta (= C. neglecta) with subsp. stricta (= subsp. neglecta, including subsp. groenlandica), subsp. inexpansa (including C. hyperborea and C. chordorrhiza), and more tentatively subsp. holmii. Also Soreng and Greene in Soreng et al. (2003) accepted three species, one with races: C. deschampsioides, C. lapponica, and C. stricta subsp. stricta (including C. neglecta), subsp. inexpansa (including C. chordorrhiza and C. hyperborea) and subsp. groenlandica (including C. holmii). Marr et al. (2007) accepted C. stricta with only two races: subsp. stricta (including "borealis-groenlandica" and C. holmii) and subsp. inexpansa.

The aggregate includes tetraploids (assumedly sexual) and higher polyploids (assumedly agamospermous). Some of the same questions are relevant here as for the C. purpurascens aggregate (above) and for the C. purpurea-canadensis aggregate (below), e.g., whether the tetraploids and the higher polyploids differ morphologically, whether the higher polyploids, if different, are autoploids or alloploids, and whether it is possible to consistently distinguish taxa within and among ploidy levels. An investigation in 2009 on a rather large body of North American and European material and a more restricted sample from Asia (ALA, BG, O, TRH, TROM) suggested the following patterns. The sexual tetraploids are divisible into four morphologically separable groups corresponding to C. deschampsioides, C. holmii, and C. neglecta subsp. neglecta and subsp. groenlandica, where subsp. groenlandica combines some features of C. holmii and subsp. neglecta. All four taxa have well-developed anthers and pollen. The agamospermous high-polyploids group into three entities morphologically: C. inexpansa and C. lapponica subsp. lapponica and subsp. sibirica with no transitions observed between C. inexpansa and C. lapponica s. lat.

Plants combining morphological features of subsp. groenlandica and subsp. neglecta sometimes have well developed anthers and pollen, sometimes partly aborting ones. Plants combining features of C. holmii and C. neglecta subsp. groenlandica always have aborting anthers. The plant named C. chordorrhiza probably belong among these sterile hybrids and are commented on among Excluded taxa and under C. holmii below. The pattern in anther and pollen abortion, combined with morphology, supports C. holmii as a species apart from C. neglecta. Calamagrostis holmii occurs sympatrically within the much larger range of C. neglecta (subsp. groenlandica). Plants combining features of C. deschampsioides and C. holmii have been named as C. kolymaensis and were considered by Tzvelev and Yurtsev to be a hybrid species of that parentage. The sparse material we have had available (from 3-4 localities) has aborting anthers, suggesting either a sterile tetraploid hybrid or a more high-polyploid apomict. We assume the former and place C. kolymaensis among Excluded taxa. The material available has been in too early developmental stage for a check on seed development.

The higher polyploids, C. lapponica and C. inexpansa (including C. hyperborea), differ from the taxa mentioned above in longer spikelets with often more acute glumes, longer ligulas, and full or nearly full anther and pollen abortion. They are seed reproducing and most probably obligately agamospermous. The distinctions from C. neglecta and among the two higher polyploids are fairly clear-cut in the material we have studied, with no obvious transitions.

The treatment below then accepts three sexual tetraploid species - C. deschampsioides, C. holmii, and C. neglecta - the latter with two subspecies, and in addition two high polyploid species - C. lapponica with two subspecies, and C. inexpansa (including C. hyperborea).