''Dendrolycopodium hickeyi'' (
synonym
A synonym is a word, morpheme, or phrase that means exactly or nearly the same as another word, morpheme, or phrase in a given language. For example, in the English language, the words ''begin'', ''start'', ''commence'', and ''initiate'' are all ...
''Lycopodium hickeyi'') known as Hickey's tree club-moss
[ or Pennsylvania clubmoss, is a North American species of clubmoss in the family ]Lycopodiaceae
The Lycopodiaceae (class Lycopodiopsida, order Lycopodiales) are an old family of vascular plants, including all of the core clubmosses and firmosses, comprising 16 accepted genera and about 400 known species. This family originated about 380 mil ...
. It is native to eastern and Central Canada (from Newfoundland to Ontario with isolated populations in Saskatchewan) and the eastern and north-central United States (from Maine west to Minnesota and south as far as Tennessee and North Carolina). The genus ''Dendrolycopodium
The genus ''Dendrolycopodium'' is a clubmoss genus in the family Lycopodiaceae. In the Pteridophyte Phylogeny Group classification of 2016 (PPG I), it is placed in the subfamily Lycopodioideae. Some sources do not recognize the genus, sinking it ...
'' is accepted in the Pteridophyte Phylogeny Group
The Pteridophyte Phylogeny Group, or PPG, is an informal international group of systematic botanists who collaborate to establish a consensus on the classification of pteridophytes (lycophytes and ferns) that reflects knowledge about plant relation ...
classification of 2016 (PPG I),[ but not in other classifications, which submerge the genus in a larger '']Lycopodium
''Lycopodium'' (from Greek ''lykos'', wolf and ''podion'', diminutive of ''pous'', foot) is a genus of clubmosses, also known as ground pines or creeping cedars, in the family Lycopodiaceae. Two very different circumscriptions of the genus are i ...
''.[
]
Description
Similar to other members of the genus, the sporophyte of ''Dendrolycopodium hickeyi'' resembles the seedlings of some conifers
Conifers are a group of cone-bearing seed plants, a subset of gymnosperms. Scientifically, they make up the division Pinophyta (), also known as Coniferophyta () or Coniferae. The division contains a single extant class, Pinopsida. All extan ...
. The upright sporophytes
A sporophyte () is the diploid multicellular stage in the life cycle of a plant or alga which produces asexual spores. This stage alternates with a multicellular haploid gametophyte phase.
Life cycle
The sporophyte develops from the zygot ...
grow from subterranean horizontal stems, often causing tree club-mosses to be found in clusters.microphylls
In plant anatomy and evolution a microphyll (or lycophyll) is a type of plant leaf with one single, unbranched leaf vein. Plants with microphyll leaves occur early in the fossil record, and few such plants exist today. In the classical concept of ...
(leaves) extending from the ground to the tips of their branches (branches 4-7mm in diameter).sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
) terminal strobilus
A strobilus (plural: strobili) is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to th ...
from which spores are released.
Identification
''Dendrolycopodium hickeyi'' is ostensibly very similar to '' D. obscurum'' which overlaps with ''D. hickeyi'' in range. While ''D. obscurum'' has reduced leaves on the underside of the branches, ''D. hickeyi'' has leaves of equal length around the branchesappressed
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...
to the stem below the first branches (unlike spreading leaves in ''D. dendroideum''). The strobilus
A strobilus (plural: strobili) is a structure present on many land plant species consisting of sporangia-bearing structures densely aggregated along a stem. Strobili are often called cones, but some botanists restrict the use of the term cone to th ...
of ''D. hickeyi'' is also intermediate in length between ''D. obscurum'' and ''D. dendroideum.''
Taxonomy
The oldest name for the taxon is ''Lycopodium obscurum'' var. ''isophyllum''.[Hickey, Ralph James. 1977. American Fern Journal 67: 47-48](_blank)
diagnosis in Latin, description and figure captions in EnglishHickey, Ralph James. 1977. American Fern Journal 67: 46
line drawings, figures 4-6 in center In elevating the plants from varietal level to species level, Wagner et al. opted to forgo the common (but not mandatory) custom of using the old varietal epithet as the new species epithet since ''D. hickeyi'' and ''D. dendroideum'' both have leaves of equal length around the branches. They chose instead the name ''Lycopodium hickeyi'' in honor of the pteridologist #REDIRECTFern
A fern (Polypodiopsida or Polypodiophyta ) is a member of a group of vascular plants (plants with xylem and phloem) that reproduce via spores and have neither seeds nor flowers. The polypodiophytes include all living pter ...
James Hickey who originally described the plant as ''L. obscurum'' var. ''isophyllum.''[Wagner, Warren Herbert, Beitel, Joseph M., & Moran, Robbin Craig. 1989. American Fern Journal 79: 119–121](_blank)
/ref>
References
{{Taxonbar, from1=Q15338232, from2=Q15322294
Lycopodiaceae
Flora of the United States
Flora of Canada
Plants described in 1977