Tuatara: Volume 26, Issue 1, September 1982
Notes on Some Anthocerotae of New Zealand (3)
Notes on Some Anthocerotae of New Zealand (3)
Taxonomy, morphology and distribution of Anthoceros laminiferus Steph. and A. muscoides Col. are reported.
Keywords: Hepaticae, Anthocerotae, Anthoceros laminiferus, A. muscoides.
The Genus Anthoceros
(iii) Anthoceros laminiferus Steph.
(a) Distribution.
A. laminiferus is found throughout New Zealand but tends to be local in any one area. It is often conspicuous in spring and early summer on the freshly exposed surface of damp banks resulting from slips, or road construction. Colenso noted on his collection packet that fresh plants have a peculiar, alga-like odour but this is not always detectable.
(b) References and sources of material.
A. laminiferus was described by Stephani (1892; 1916) from specimens collected in New Zealand by W. Colenso. An examination was made of the holotype (Colenso, a 1283) held at the Stephani Herbarium, Geneva and of the sheet of notes and drawings (No. 734) made by Stephani; also of isotypes at the National Museum, Wellington, at the British Museum and in the Hodgson collection. Three additional specimens which were examined were collected and named by E. A. Hodgson (MPN 18554, 18555, 18556). Fresh material was obtained from Stewart Island, Nelson and Palmerston North.
page 21(c) Morphology of the gametophyte.
Plants occur either singly or aggregated into colonies (Fig. 1). They usually lie horizontally and are attached to the soil by rhizoids. Each rather firm to gelatinous, emerald to olive-green thallus has a basal costate region up to 1mm wide, then broadens abruptly into a more or less circular to reniform, simple or branched lamina 0.8-2.0 (-4.0) cm wide. The border is deeply cut into laciniate lobes (Figs. 1 and 2).
The antical surface in branches or plants which are sterile or male is generally plane apart from occasional lamellate outgrowths which often run lengthwise but in ones with archegonia the margins tend to be upturned and connivent so producing a shallow cup. The lower surface medianly is strongly convex or doubly convex for, as noted by Stephani (1892), forking of the costa takes place long before the frond becomes visibly bipartite.
Plants are generally monoecious with antheridia appearing on the same branches as the archegonia. However, some branches or even whole plants may be sterile or male. The antheridial cavities contain up to 8 or more antheridia, each with a short stalk and a body 0.1-0.24mm long. One, or sometimes two, archegonia are commonly present on each main branch of the thallus.
(d) Anatomy of the thallus.
As seen in a transverse section thalli with archegonia are thicker than male or sterile ones. In the latter there is a costate median region up to 0.8mm deep which narrows rather abruptly to a depth of 0.3mm and then more gradually towards the margin. Corresponding figures for plants with archegonia are 1.3 and 0.5mm. In addition to the cavities occupied by Nostoc there are numerous schizogenous cavities which are usually filled with mucilage (Fig. 3). Chlorophyllous cells each have a single chloroplast.
(e) Morphology of the sporophyte.
Dehiscing sporophytes are 1-6cm high surrounded at the base by an involucre 5mm in height. The capsule has stomata in the epidermis and opens as in A. laevis (Campbell, 1981) by one or two slits which do not reach the apex. In dry air the valves twist spirally (Fig. 2). The brown-black spores have a maximum diameter of 42-58 microns. The surface shows reticulate marking, the triradiate face being reticulate-foveate (Fig. 4a), while on the ridges of the spherical face there are numerous simple or twinned spines 2.5-3.5 microns high (Fig. 4b). Pseudoelaters are formed of 2 to 6 cells without helical thickening.
Notes
Production of sporophytes apparently exhausts the gametophyte which commonly dies off both in nature and in culture as the capsules mature. However, either regenerative branches from the thallus edge or entire plants with few or no sporophytes may persist into a second year.
A. laminiferus probably derives its species name from the leaf-like appearance of the thallus with a broad lamina and a stalk-like base. It corresponds in many respects with A. punctatus L., a species which is best-known from the Mediterranean-Atlantic region of Europe but as well is recorded from Macaronesia, North and South Africa, North and South America and Asia (Paton, 1979). However, the thallus of A. laminiferus may generally be distinguished by its larger size and more deeply dissected margin.
(iv) Anthoceros muscoides Col.
(a) Distribution.
Fig. 4. Spore a. triradiate face, b. outer face. (A. laminiferus). Scanning electron micrographs by G. Walker.
(b) References and sources of material.
(c) Morphology of the gametophyte
The plants are caespitose, growing over one another in soft, mossy colonies (Fig.5), up to 5cm across and basally attached to the soil by rhizoids. The colour of dry plants is dull yellow-green to green but when wet and viewed under a X10 lens or a stereomicroscope it is translucent green. The thallus has a smooth basal portion, at first about 1 mm wide, which is either plane, or shallowly trough-shaped due to upturned lateral margins. It gradually broadens into a distal portion up to 6mm wide. This is cut into laciniate lobes which are often erect or incurved, have crenate, undulate margins, and carry numerous lamellae. Plants are monoecious. The numerous immersed antheridial cavities each contain up to 5 antheridia at varying stages of development, all arising from a common base. The antheridium has a stalk of up to 4 tiers of cells and a body up to 0.13mm long and 0.09mm wide. One or sometimes two immersed archegonia appear on each main lobe.
(d) Anatomy of the thallus.
Fig. 6. Diagram of part of a transverse section of the thallus. 1. lamella, m. mucilage cavity. A. muscoides.
(e) Morphology of the sporophyte.
The sporophyte is surrounded at the base by a cylindrical involucre 2 to 4mm high. The capsule, 3-6cm long, at first is green and erect but later black and drooping. It has a very thin wall and stomata in the epidermis. Other epidermal cells are long and narrow with slightly thickened walls except for thin-walled cells at the 2 dehiscence lines. The capsule opens lengthwise into 2 valves which twist spirally and for a time remain united at the tip. The brown-black spores have a diameter of 40-50 microns. The surface shows reticulate marking, the triradiate face being reticulate-foveate (Fig. 7a), while on the ridges of the spherical face there are numerous simple or occasionally twinned spines 1.5-2.5 microns high (Fig. 7b). Pseudoelaters, 75-250 microns long, are formed of 2-6 cells without helical thickening and may be branched or V-shaped.
Notes
1. |
Plants normally die off when the spores are shed but under favourable conditions regenerative shoots arise from the old thallus. Regeneration may also take place from lamellae which are readily detachable. |
2. |
Characters which distinguish A. laminiferus from A. muscoides. |
Character | A. laminiferus | A. muscoides |
Thallus texture | Rather firm to gelatinous. | Thinner and spongy |
Thallus colour | Emerald to olive-green | Yellow-green to green |
Thallus shape | Distally tends to be shallowly cup-shaped and costate | Basally tends to be trough-shaped, distally broader and frilled. |
Mature capsule | More or less erect; brown-black | Drooping; black |
Spore diameter | 42-58 microns | 40-50 microns |
Spine length | 2.5-3.5 microns | 1.5-2.5 microns |
3. |
The status of Anthoceros helmsii Steph. |
Fig. 7. Spore (a) triradiate face, (b) spherical face. A. muscoides. Scanning electron micrographs by G. Walker.
References
Campbell, E. O. 1981. Notes on some Anthocerotae of New Zealand. Tuatara 25:7-13.
Colenso, W. 1884. A further contribution towards making known the botany of New Zealand. Transactions of the New Zealand Institute 13:361.
Paton, Jean A. 1979. Anthoceros agrestis, a new name for A. punctaty var. cavernosus sensu Prosk. 1958, non (Nees) Gottsche et al. Journal of Bryology 10:257-261.
Stephani, F. 1892. Colenso's New Zealand Hepaticae. Journal of the Linnean Society of London (Botany)29:266.
—— 1893. Hepaticarum species novae. Hedwigia 32:142.
—— 1916. Species hepaticarum 5:1006-1007. Geneva.