Panarctic Flora

3309044-045 The Carex capillaris aggregate C. capillaris, C. krausei

Geography: Circumboreal-polar.

Notes: Elven: Our opinion is that Carex capillaris and C. krausei are well delimited species, too different to be encompassed in an aggregate. Carex capillaris is polymorphic but no part of its polymorphy approaches the morphology of C. krausei. This view is, however, not shared by other authors.

The arctic and northern plants of this group have been variously treated as one (C. capillaris), two (C. capillaris, C. krausei), four (C. capillaris, C. fuscidula, C. krausei, C. boecheriana), or even more species. Egorova (PAF proposal) accepted four species, for North America mainly based on the treatment of Löve et al. (1957). This treatment is heavily based on non-vouchered and in several cases improbable or obviously wrong chromosome numbers and is an untrustworthy source of information, see Ball's note to the chromosome reports for C. williamsii above. What Ball did not discuss is that the untrustworthiness also extends to the morphological treatment.

Ball: Although I treated this group as two species in Ball (2002b), I have very serious doubts about them. Carex krausei seems to appear sporadically throughout most of the range of C. capillaris, and gynaecandrous spikes can occur sporadically in a population and perhaps even on different culms of the same plant with staminate terminal spikes. Unfortunately it will be necessary for someone to rework this group from the beginning, ignoring everything that has been done before (especially by the Löves).

Elven and Murray: We disagree with Dr. Ball on this matter. We have observed both species for many years in the field in many regions (Siberia, Alaska, Canada, Iceland, Svalbard), frequently within the same sites, and we find them consistently different, easy to keep apart and without transitions. We do not rely only on the gynaecandrous terminal spikes in C. krausei (which we agree may occur sporadically in populations of C. capillaris, as well as do occasional staminate terminal spikes in populations of C. krausei), but also on, e.g., shape and direction of spikes, shape and colour of the perigynia, and shape and colour of the pistillate scales. The spikes of C. krausei are nearly linear, keep nearly erect until (or even past) the fruit stage, and are dense with much more numerous, smaller perigynia. The terminal (gynecandrous) spike is almost always long-pedunculate and reaches above the other spikes, whereas the terminal (staminate) spike in the sympatric C. capillaris subsp. fuscidula is very short-pedunculate and is much overtopped by the 1-2 nearest pistillate spikes. It is indicative that in Alaska, where most botanists have field experience with both species, not a single specimen of C. krausei or C. capillaris in the herbarium (ALA) was misidentified by the collectors. We accept two species: C. capillaris with three races, and C. krausei.