| Huperzia | |
|---|---|
 | |
| Huperzia selago in Austria | |
Scientific classification | |
| Kingdom: | Plantae |
| Clade: | Tracheophytes |
| Clade: | Lycophytes |
| Class: | Lycopodiopsida |
| Order: | Lycopodiales |
| Family: | Lycopodiaceae |
| Subfamily: | Huperzioideae |
| Genus: | Huperzia Bernh.[1] |
| Species | |
Huperzia is agenus oflycophyte plants, sometimes known as thefirmosses orfir clubmosses; theFlora of North America calls themgemma fir-mosses.[2] This genus was originally included in the related genusLycopodium, from which it differs in having undifferentiated sporangial leaves, and the sporangia not formed into apical cones. The common namefirmoss, used for some of the north temperate species, refers to their superficial resemblance to branches offir (Abies), aconifer. As of 2020[update], two very differentcircumscriptions of the genus were in use. In thePteridophyte Phylogeny Group classification of 2016 (PPG I),Huperzia is one of three genera in the subfamilyHuperzioideae of the familyLycopodiaceae. Most species in the subfamily are placed in the genusPhlegmariurus.Huperzia is left with about 25 species,[3] although not all have been formally transferred to other genera.[4] Other sources recognize onlyHuperzia, which then has about 340 species.[5]
Thesporophytes of this genus have unbranched shoots that are generally upright and round in cross section. Horizontal stems are absent. The leaves are not borne in distinct ranks, and are usually somewhat lanceolate in shape. In some species, they vary in size according to the season in which they grow. Branchlets bearing gemmae – bud-like structures by which the plant reproduces asexually – occur among the leaves. The gemmae are triangular, with eight leaves in a constant pattern: four flattened into a plane and two large lateral leaves. Thesporangia are kidney-shaped (reniform), occurring at the base of a leaf that is either unmodified or reduced. The roots are produced near the apex of shoots, and migrate downwards inside the cortex of the stem to emerge at soil level. The unbranchedgametophytes are not photosynthetic, but rather subterranean andmycorrhizal.[2]
TheFlora of North America distinguishesHuperzia from theepiphytic tropical genusPhlegmariurus on the basis of differences such as the former's complex and specialized shoots, the gemmae and the branchlets on which they are borne, and the unbranched gametophytes.[2]
The genusHuperzia was created byJohann Jakob Bernhardi in 1801. Bernhardi separatedHuperzia fromLycopodium. Thetype species isLycopodium selago which becameHuperzia selago.[1]
In thePteridophyte Phylogeny Group classification of 2016 (PPG I),Huperzia is placed in the subfamilyHuperzioideae of the familyLycopodiaceae.[3] Aphylogenetic study in 2016, employing both molecular and morphological data, concluded that either a one-genus or a three-genus division of the subfamily producedmonophyletic taxa. The authors preferred the three-genus division, recognizingHuperzia,Phlegmariurus andPhylloglossum. Their preferred hypothesis for the relationships of the three genera was:[6]
The majority of the species formerly placed in a broadly definedHuperzia belong inPhlegmariurus.[6] Earlier, theFlora of North America had also separatedHuperzia fromPhegmariurus.[2] However,Phlegmariurus is difficult to separate morphologically, and others have preferred the one-genus division of the subfamily.[7][5]
The PPG I classification stated there were 25 species in the genusHuperzia.[3] As of June 2024[update],World Ferns listed the following species, noting that "many species still need transfer into other split genera".[4]
The following hybrids have been described:[4]
Ascircumscribed in the PPG I classification,Huperzia is distributed in temperate, arctic and alpine habitats, including mountains in tropical Asia.[4] Its species are terrestrial or grow on rocks.[2]Phlegmariurus isepiphytic,[2] and has a worldwide tropical distribution,[7] so whenHuperzia is defined broadly to include all three genera of the subfamily Huperzioideae, it has an almost worldwide distribution, absent mainly in North Africa, the Arabian Peninsula and Western Asia.[5]