Tuatara: Volume 1, Issue 3, September 1948
A Note on Lichens with a Key to the Commoner New Zealand Genera
A Note on Lichens with a Key to the Commoner New Zealand Genera
Lichens form a plant group apart, as the body consists of a fungus and an alga growing together to form the lichen thallus. The exact relations between the fungus and the alga are still subjects of discussion, but the group is morphologically so distinct that it may best be treated as a separate division of the plant kingdom (LICHENES, or if you will MYCOPHYCOPHYTA!) The division is split up into subdivisions, orders, families, genera and species, the classification being based primarily on the structure of the fungal fruit, and secondarily on the nature of the alga. A few tropical genera have fungal elements belonging to the HYMENOMYCETES, but the bulk are associated with ASCOMYCETES. These ASCOLICHENES are divided into page 21 the PYRENOCARPEAE with a closed fructification (perithecium), and the (GYMNOCARPEAE) with an open fructification (apothecium).
The alga present belong either to the CHLOROPHYCEAE, “green algae”, or the MYXOPHYCEAE, “blue-green algae”. It is usually possible, simply by moistening the specimen, to decide to which group the alga of a particular lichen belongs, but in refined classifications one has to determine more closely the relationship of the lichen alga to the free-living alga.
Zahlbruckner (Pflanzenfamilien, 1926) recognised 54 families (35 in New Zealand), 375 genera (about 80 in New Zealand), and about 9700 species (over 600 in New Zealand). Very many more remain to be discovered, and probably hundreds in New Zealand.
Lichens are the most truly cosmopolitan group of plants, being absent only from areas covered by perpetual snow or water. They succumb, however, to the smoke of heavily industrialised areas. You can, if you care to risk the attention of the police, gather lichens on the walls of the Wellington Bank of New Zealand, but not on those of the London Branch. Arid deserts, humid forests, coastal spray-sprinkled rocks and ice-surrounded rocks of high mountains are all habitats yielding their species. The elegant little red thallus of Caloplaca elegans has been gathered a few feet above high-tide level on Rangitoto Island, and just below the summit of Mt. Tapuaenuku (9465 feet). The range of habitats is very great, even glass, iron, charcoal, leather, linoleum and tarred cloth are not immune. Xanthoira parietina (Fig. 38) will seize on and brighten a rock, an animal skeleton, or a tree trunk, while certain lichens are strictly confined to one particular habitat, e.g., certain species of Verrucaria do not live away from rocks periodically submerged by the tide. Limestone rocks and basaltic rocks have different assemblages of genera and species, and the ecology of lichens becomes fascinating once a reasonable knowledge of the genera and species has been gained.
The first important work on the lichens of New Zealand was that of Babington in Hooker's Flora Novae Zelandiae of 1885, based largely on collections made by Colenso and Lyall. In Hooker's “Handbook” of 1867, forty-four genera and 212 species were listed, many of which were referred to European species, but are now considered distinct. New species were described in the early volumes of the Transactions of the New Zealand Institute, especially by Knight, who built up a considerable herbarium. In 1888 Nylander published his Lichenes Novae Zelandiae, listing 371 species, 97 of which he considered to be identical with European species.
The study of our lichens then languished; meanwhile much critical work was being done in Europe and new conceptions of generic and species limits evolved. Of recent years local botanists have shown page 22 renewed interest, and in 1941 Zahlbruckner published his monograph, Lichenes Novae Zelandiae, based on collections, largely those of the late J. S. Thomson of Dunedin. At present only a very few copies of this work are available in New Zealand. Large collections of Cladonia were sent to Sandstede, the outstanding authority on this genus. As a result local botanists can now pursue their studies with more confidence.
The best book in English for any one taking up the study of lichens is “Lichens” by the late Annie Lorraine Smith, 1921, in the “Cambridge Botanical Handbooks.” This deals with all aspects of the subject, is well illustrated, and should be in the libraries of all University Colleges. A useful short work, with good keys to the genera, is that of W. Watson, “The Classification of Lichens” which appeared in the New Phytologist, Vol. 28, 1929.
Key to The Commoner Genera of N.Z. Lichens
|1.||Thallus gelatinous, more or less translucent when wet, algae scattered or in chains (Fig. 2)||2|
|Thallus not gelatinous, not translucent when wet, algae in a definite layer or group (Fig. 5)||7|
|2.||Thallus minutely fructiculose||3|
|Thallus foliose, or swollen and nostoc-like||5|
|3.||Plant found only on coastal tidal rocks (Fig. 1)||Lichina|
|Plant found inland, never on tidal rocks||4|
|4.||Plant forming tiny clumps with crowded branches||Polychidium|
|Plant more openly branched, tree-like||Dendriscocaulon|
|5.||Apothecia immersed in thallus, with minute opening||Pyrenocollema|
|Apothecia superficial with flat disc||6|
|6.||Thallus with distinct cortex (Fig. 3)||Leptogium|
|Thallus without a cortex (Fig. 2)||Collema|
|7 Thallus fruticose in habit (Fig. 28)||8|
|Thallus foliose, squamulose or crustaceous||28|
|8.||Thallus with basal squamules and erect podetia (Fig. 23)||9|
|Thallus not so differentiated||12|
|9.||Podetia short, simple or with leaf-like lobes above||10|
|Podetia branched and/or ending in cup-like expansions||11|
|Podetia not widening and lobing upwards||Baeomyces|
|Podetia widening and lobing upwards||Thysanothecium|
|11.||Podetia hollow (Fig. 23)||Cladonia|
|12.||Thallus of minute filaments, matted together||13|
|Thallus of cylindrical or srap-shaped bodies (Fig. 30)||14|
|14.||Thallus segments strap-shaped (Fig. 30)||15|
|Thallus segments cylindrical, not flattened (Fig. 28)||20|
|5.||Thallus horny when dry, brown, stiff, with spinulose projections||Cetraria|
|Thallus not with the above characters in combination||16|
|16.||Thallus distinctly yellow or red (Fig. 27)||Teloschistes|
|Thallus neither yellow nor red||17|
|17 Spores visible as a black powder (Fig. 33)||Sphaerophorus|
|Spores not exposed as a black powder||18|
|18.||Plant forming dense small masses of short erect flattened segments||Siphula|
|Plants not forming dense masses of this type||19|
|19.||Thallus segments spreading more or less horizontally, usually showing rhizines and cilia||Anaptychia|
|Thallus segments tufted, lacking rhizines and cilia (Fig. 30)||Ramalina|
|20.||Spores exposed as a black powdery mass||Sphaerophorus|
|Spores not exposed||21|
|21.||Thallus of dark more or less felted filaments||Parmelia|
|Thallus not of dark felted filaments||22|
|22.||Branches bearing obvious cephalodia||Stereocaulon|
|Branches not bearing cephalodia||23|
|23.||Plant forming dense crowded masses of short tapering white hollow cylinders||Thamnolia|
|Plant not showing the above characters in combination||24|
|24.||Thallus with few, usually elongate, branches||25|
|Thallus much branched||26|
|25.||Central cylinder loose||Alectoria|
|Central cylinder stout, flexible (Fig. 19)||Usnea|
|26.||Thallus forming branches forming entangled cushion-like masses on soil, dying below||Cladonia|
|Thallus with a single point of attachment, not dying below||27|
|27.||Branches terete or angled, with solid central cylinder (Fig. 19)||Usnea|
|Branches dorsiventral, somewhat flattened, without distinct solid central cylinder||Anaptychia|
|28.||Thallus foliose, attached to the substratum by a central umbilicus, or at several to many points by rhizines||29|
|Thalus squamulose or crustaceous, attached very tightly to the substratum, or occasionally developed beneath the surface||44|
|29.||Thallus attached by a central umbilicus||30|
|Thallus attached at several or many points||31|
|30.||Thallus more or less copper-coloured below||Heppia|
|Thallus completely black on both surfaces||Umbilicaria|
|31.||Apothecia appressed to surface of thallus, without thalline margin||32|
|Apothecia more or less raised from surface of thallus, usually with thalline margin||34|
|32.||Apothecia on surface of thallus and more or less sunken, lower surface of thallus more or less copper-coloured||Solorina|
|Apothecia terminal at tips of lobes||33|
|33.||Apothecia on upper surface of lobes (Fig. 4, 24)||Peltigera|
|Apothecia on lower surface of lobes||Nephroma|
|34.||Upper surface of thallus distinctly yellow or red||Xanthoria|
|Upper surface neither yellow nor red, there may be yellow showing in spots or cracks||35|
|35.||Under surface with cyphellae or pseudocyphellae (Fig. 5, 6)||Sticta|
|Under surface with neither cyphellae nor pseudocyphellae||36|
|36.||Thallus with reticulate, spongy outgrowth below (Fig. 22)||Anzia|
|Thallus without reticulate, spongy outgrowth below||37|
|37.||Apothecia with a thalline margin (Fig. 13)||38|
|Apothecia without a thalline margin (Fig. 11)||42|
|38.||Spores 2, or more, celled (Fig. 18)||39|
|Spores 1 celled (Fig. 12)||40|
|39.||Thallus about circular in outline||Physcia|
|Thallus not at all circular in outline||Lobaria|
|41.||Thallus lobes narrow||Psoroma|
|Thallus lobes broad, or, if narrow, then with oval perforations||Parmelia|
|42.||Upper surface of thallus felted||Erioderma|
|Upper surface of thallus not felted||43|
|43.||Cortical hypae parallel to surface (Fig. 20)||Coccocarpia|
|Cortical hyphae perpendicular to surface (Fig. 21)||Parmeliella|
|44.||Thallus squamulose, with distinct lobes (Fig. 7)||45|
|Thallus crustaceous, not distinctly lobed||52|
|45.||Apothecia with minute opening||Dermatocarpon|
|Apothecia with distinct disc||46|
|46.||Apothecia without thalline margin, disc black||47|
|Apothecia with thalline margin, disc not black||48|
|47.||Spores 1 celled, colourless (Fig. 12)||Lecidea|
|Spores 2-4 celled, brownish (Fig. 18)||Buellia|
|49.||Spores brown, thallus white or greyish||Physcia|
|Spores colourless, thallus otherwise coloured||50|
|50.||Apothecia not more than 1 mm. across, yellow or red, thallus lobes distinct only at margins||Caloplaca|
|Apothecia layer, thallus lobes well developed||51|
|51.||Thallus easily lifted from substratum, yellowish or red Xanthoria Thallus separated from substratum with difficulty, shades of brown, cephalodia usually present||Lecanora|
|52.||The crustaceous lichens cannot be satisfactorily keyed without resource to microscopic features, and are left for a further communication.|
Key to the Groups of Stictaceae
The two genera of this family—Sticta and Lobaria, are fairly readily grouped into sub-genera, which are now often treated as genera. There are over 50 species in New Zealand, all groups being represented
|1.||Thallus without cyphellae or pseudocyphellae on the lower surface||2|
|Thallus with either cyphellae or pseudocyphellae on the lower surface||3|
|3.||Thallus with cyphellae||4|
|Thallus with pseudocyphellae||5|
The last two may each be again divided according as the pseudocyphellae are white or yellow.
Key to the Groups of Parmelia
The genus is also represented by over 50 species in New Zealand. The different groups, some often treated as separate genera, may be keyed as follows:
|1.||Rhizines never present, lower cortex thick and rough||2|
|Rhizines always present, lower cortex never thick and rough||3|
|2.||Thallus with oval perforations||Menegazzia|
|Thallus without perforations||Hypogymnia|
|3.||Thallus fruticose lobes channelled||Pseudevernia|
|Thallus foliose, lobes never channelled||Euparmelia|
|The subgenus Pseudevernia has not so far been met with in New Zealand. Euparmelia may be grouped as follows:|
|1.||Rhizines small and evenly distributed||2|
|2.||Thallus dark, shades of brown||Melanoparmelia|
|Thallus light, shades of yellowish green||Xanthoparmelia|
|3.||Rhizines evenly distributed||Hypotrachyna|
|Rhizines at points of contact with substratum, margins nude||Amphigymnia|
Key to the Groups of Cladonia
Cladonia (Figs. 23, 29, 31) is represented by about 40 species in New Zealand, but there is considerable difference of opinion as to species limits in the genus, and some classifications would raise the number to about 70. The groups, or sub-genera, are fairly well defined as follows:
|1.||Podetia repeatedly and intricately branched, forming cushion-like masses, dying at the base, never bearing cups of squamules, seldom sorediose; primary thallus evanescent, rarely seen||2|
|Podetia, if branched then not forming entangled cushsion-like masses, not dying at base, often bearing cups and/or squamules, frequently sorediose, primary thallus persistent||5|
|2.||Podetial branches with very frequent and striking perforations (Fig. 25)||Clathrina|
|Podetial branches not perforate, or with very few hardly noticeable perforations||3|
|Plant not brown, or if so not densely branched||4|
|4.||Plant white, faintly yellowish, or grey||Cladina|
|Plant yellowish, yellowish green or brownish, but not forming intricately branched masses; branches easily broken||Unciales|
|5.||Primary thallus crustaceous (group not so far met with in New Zealand)||Pycnothelia|
|Primary thallus squamulose||Cenomyce||6|
|Apothecia brown, flesh-coloured or wax-yellow||Ochrophaeae||7|
|7.||Thallus squamules absent or scanty, podetia lacking squamules and soredia||Unciales|
|Thallus squamules well developed, podetia often squamulose and/or sorediose, not so easily broken as in Unciales||8|
|8.||Podetia with open axils and cups||Chasmariae|
|Podetia with closed axils and cups||Clausae|
The student must understand that the forms of Cladonia are manifold, and no manageable key will provide for all possible combinations of characters. If desired a key to the more important species will be given later.
It is assumed that the student has a general knowledge of the structure of lichens. A rather full glossary is given, to serve the needs of subsequent articles. Illustrations will also be given with later articles.
- AMORPHOUS, of a cortex formed of indistinct hyphae with thickened walls.
- AMPHITHECIUM, thalline margin of the apothecium. (Fig. 13.)
- APOTHECIUM, an open or disc-shaped fructification. (Figs. 9, 10, 11, 13.)
- AREOLA, small space marked out by lines of chinks on the surface of the thallus.
- ASCOMYCETES, a group of fungi in which the spores (usually 8) are formed inside a more or less pyriform body the ascus. (Fig. 13.)
- ASCUS, an enlarged cell in which a definite number of spores (usually 8) are developed. (Fig. 13, E.)
- ASCYPHOUS, of podetia without SCYPHI. (Fig. 31.)
- AXIL, the inner junction of a branchlet with a branch or with another branchlet. (Fig. 28.)
- BIATORINE, of apothecia that are soft and waxy, and often brightly coloured.
- BYSSOID, slender, thread-like.
- CAPITULUM, a globose apical apothecium as in SPHAEROPHORUS.
- CEPHALODIUM, irregular outgrowth from the thallus enclosing mostly blue-green algae (the thallus itself containing blue-green algae). (Fig. 7, 14.)
- CHLOROPHYCEAE, a group of Algae in which the chloroplasts are bright green.
- CHLOROPLASTS, the individual plastids or “granules” containing chlorophyll, of an agla or a higher plant.
- CHONDROID, hard and tough like cartilage, applied to strengthening hyphal strands. (Fig. 19.)
- CILIUM, hair-like outgrowth from the surface or margin of a thallus, peculiar to the STICTACEAE. (Fig. 5.)
- DECOMPOSED, of a cortex formed of gelatinous indistinct hyphae.
- DETERMINATE, of a thallus with a definite outline.page 28
- DIMIDIATE, of a perithecium when the outer wall covers only the upper portion.
- ENDOGENOUS, produced internally, as spore in an ascus. Used also of a thallus in which the algae predominate.
- ENTIRE, of a perithecium completely surrounded by an outer wall.
- EPIPHLOEODAL, of a thallus growing on the surface of bark.
- EPITHECIUM, upper layer of the thecium. (Fig. 13, C.)
- EXOGENOUS, produced externally as spore on the tips of hyphae. (Fig. 29.) Used also of a thallus in which the fungus predominates.
- FASTIGIATE, of a cortex formed of clustered parallel hyphal branches perpendicular to the long axis of the thallus.
- FIBROUS, of a cortex formed of hyphae parallel to the long axis of the thallus.
- FOLIOSE, of lichens with a leafy form and stratose in structure. (Fig. 32.)
- FOVEOLATE, pitted. (Fig. 35.)
- FRUTICOSE, of an upright or pendulous thallus, mostly with radiate structure. (Fig. 28.)
- GONIDIA, the agal constituents of the thallus (Fig. 9); sometimes restricted to the green algae, the term for blue-green algae then being GONIMIA.
- GYROSE, curved backward and forward, used of the furrowed fruit of certain species of UMBILICARIA.
- HETEHOMEROUS, when the fungal and alga constituents are in definite strata, as in PARMELIA.
- HOLD-FAST, attachment organ of thallus. (Fig. 30.)
- HOMIOMEROUS, when the fungal and algal constituents are more or less mixed, as in COLLEMA.
- HYMENIUM, apothecial tissue consisting of asci and paraphyses. (Fig. 13.)
- HYMENOMYCETES, a group of fungi in which the spores are borne in groups of 4 on undivided basidia or stalks.
- HYPHAE, the thread-like branches of the vegetative part of a fungus.
- HYPOPHLOEODAL, of a thallus growing within the bark.
- HYPOTHALLUS, the first growth of hyphae persisting as a hypal growth at the base or margin of the thallus.
- HYPOTHECIUM, the layer below the thecium. (Fig. 13, G.)
- INTRICATE, of a cortex in which the hyphae are densely interwoven, but not coalescent.
- ISIDIA, coral like outgrowths on the thallus. (Fig. 17.)page 29
- LECANORINE, of an apothecium with a thalline margin. (Fig. 26.)
- LECIDEINE, of a thallus, usually dark coloured, without a thalline margin. (Fig. 11.)
- LEPROSE, mealy or scurfy.
- LIRELLA, a narrow long apothecium, as in the GRAPHIDACEAE.
- MAZAEDIUM, a fructification where the spores lie as a powdery mass in the capitulum, as in SHAEROPHORAS.
- MEDULLA, the loose hypal layer in a thallus. (Fig. 5.)
- MULTI-SEPTATE, of spores with numerous transverse septa.
- MURIFORM, of spores divided like a brick-work wall.
- MYXOPHYCEAE, a group of algae in which the chloroplasts are blue-green.
- NOSTOC-LIKE, resembling the more or less globular gelatinous colonies of the blue-green alga NOSTOC.
- PALISADE-CELLS, the terminal cells of hyphae forming a fastigiate cortex.
- PANNIFORM, having a felted or matted appearance.
- PARAPHYSES, the sterile filaments of the HYMENIUM. (Fig. 13.)
- PARATHECIUM, hyphal layer round the apothecium. (Fig. 13, F.)
- PELTATE, of orbicular and horizontal apothecia in the form of a shield.
- PERITHECIUM, fructification, usually roundish and with a minute apical opening or OSTIOLE. (Fig. 8.)
- PERVIOUS, of SCYPHI with an opening at the base.
- PLACODIOID, of a thallus with a squamulose determinate outline, more or less orbicular.
- PODETIUM, stalk-like or branched secondary thallus of the CLADONIACEAE. (Fig. 23.)
- POLARILOCULAR, of two-celled spores with a thick median wall, traversed by a connecting tube.
- PROPER MARGIN, the hyphal margin surrounding the apothecium. (Fig. 13, B.)
- PSEUDOCYPHELLAE, point-like eruptions, usually on the lower surface, on the thallus of certain species of STICTA, with extruded hyphal filaments.
- RADIATE, of a thallus in which the tissues radiate from a centre as in USNEA.
- RHIZINE or RHIZOID, attaching “rootlets” on the lower surface of thallus. (Fig. 24.)
- RIMOSE, cleft or chinked into AREOLAE.
- SCYPHUS, cup-like expansion of podetium in CLADONIA. (Fig. 23.)page 30
- SORALIUM, a group of soralia surrounded by a definite margin. (Fig. 16.)
- SQUAMULE, a small thalline lobe or scale. (Fig. 7, 23.)
- STRATOSE, of a thallus with the tissues arrayed in horizontal layers.
- TERETE, rounded in transverse section, as in the branches of USNEA.
- THALLINE MARGIN, of an apothecium with a margin formed of and usually coloured like a thallus. (Fig. 13, A.)
- THALLUS, the vegetative body of a lichen.
- THECIUM, a layer of tissue in the apothecium consisting of asci and paraphyses. (Fig. 13, D.)
- UMBILICUS, the lower point of attachment of a thallus attached to the substratum at a central point only.
Legends to Figures
Lichina, × 5.
Collema, × 20.
Leptogium, × 20
Peltigera, × ½.
Cyphella, × 200.
Pseudocyphella, × 200.
Lecanona, showing lobate squamules and cephalodia, × 4.
Apothecium, with gonidia in thalline margin.
Apothecium, without gonidia in the thalline margin.
Apothecium, lecideine type.
Apothecium, showing (a) thalline margin; (b) proper margin; (c) epithecium; (d) thecium; (e) ascus; (f) parathecium; (g) hypothecium.
Cephalodium, on normal thallus.
Usnea, transverse section showing central chondroid cylinder.
Cortex, with hyphae parallel to surface.
Cortex, with hyphae perpendicular to surface.
Anzia, showing spongy outgrowth below.
Cladonia, with basal squamules and podetium enlarging above into scyphus.
Peltigera, under surface showing “veins” and rhizines.
Cladonia (Clathrina), showing perforated branches of podetia.
Apothecia of lecanorine type.
Teloschistes, showing ciliate apothecia and branches.
Usnea rubescens, showing holdfast, × 2/3.
Cladonia scabriuscula, × 2/3.
Cladonia cornutoradiata, × 2/3.
Ramalina leiodea, × 2/3.
Sticta filix, × 2/3.
Sphaerophorus australia, × 2/3.
Sticta coronata, × 2/3.
Sticta impressa, × 2/3.
Lobaria adscripta, × 2/3.
Parmelia caperata, × 2/3.
Xanthoria parietina, × 2/3.
Collema leucocarpon, × 2/3.