Flora of North America species comparison

Reports of Gentiana parryi outside the range indicated here have been based on specimens of G. calycosa or G. affinis (studies for this flora). Because of its restriction to high altitudes, populations of G. parryi are widely scattered, especially in the southern part of its range.

Gentiana parryi has sometimes been included in G. calycosa and less often in G. affinis, but its larger, conduplicate involucral leaves, which are more or less sharply differentiated from the distal cauline leaves and largely envelop the calyces, give G. parryi an aspect distinctly different from that of either G. calycosa or G. affinis. Biometric studies by J. R. Spence (unpubl.) have supported its recognition as a species. As noted by N. H. Holmgren (1984b), these species also differ in anther length, which is 3.5–5 mm in G. parryi and 1.6–3.2 mm in G. calycosa and G. affinis. In the Rocky Mountains of central Colorado, G. parryi and G. affinis appear especially well differentiated. Where the ranges of G. parryi and G. calycosa approach each other in the Intermountain Region, G. parryi usually grows in drier habitats than G. calycosa. The distinctive involucre of G. parryi is less well developed in some Arizona plants otherwise identifiable as this species, which should be given further study.

(Discussion copyrighted by Flora of North America; reprinted with permission.)

In contrast to the deep green stems and leaves of Gentiana prostrata, the vegetative parts of G. fremontii are much paler. G. Engelmann (1879) described plants of G. fremontii as having a pale, sickly appearance, and J. A. Ewan annotated specimens as having been yellowish when seen in the field, reminiscent of a fungus or broomrape (Aphyllon or Orobanche). This suggests that mycorrhizal symbiosis is especially significant in this species, but its trophic ecology has not been studied.

Gentiana fremontii differs further from G. prostrata in having obovoid capsules less than twice as long as wide, generally not fully exserted from the marcescent corolla, narrowly winged distally along the sutures, with valves that eventually separate nearly to the base, whereas the capsules of G. prostrata are compressed-cylindric, more than twice as long as wide, often fully exserted at maturity, not winged, with the valves separating only above the middle. Also, although both species vary in this respect, G. fremontii more often has the flower parts in fives.

The names Gentiana aquatica Linnaeus and Chondrophylla aquatica (Linnaeus) W. A. Weber have often been applied to this species. Gentiana fremontii, although similar to the Siberian and Chinese G. aquatica, appears to differ consistently in the wider, more conspicuous white margins of its leaves, longer and proportionately narrower mid-cauline leaves, usually white rather than blue corollas, and corolla plicae that generally have jagged rather than entire summits. The illegitimate name G. humilis Steven 1812, not Salisbury 1796, has also been applied to G. fremontii, but the North American plants are not now considered conspecific with the type from Azerbaijan.

(Discussion copyrighted by Flora of North America; reprinted with permission.)