Fissidens Grandifrons: a Possible Explanation for the Rarity of Sporophytes RONALD A. PURSELL1 & JAMES R. SHEVOCK
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Polish Botanical Journal 58(2): 475–480, 2013 DOI: 10.2478/pbj-2013-0057 FISSIDENS GRANDIFRONS: A POSSIBLE EXPLANATION FOR THE RARITY OF SPOROPHYTES RONALD A. PU R SELL 1 & JAMES R. SHEVOCK Abstract. Perigonia are described for the first time in Fissidens grandifrons Brid. A possible explanation for the rarity of sporo- phytes in this species, the result of perigonial and perichaetial plants separated in different mats, is presented. Sexual reproduction in F. grandifrons is compared with that of F. perdecurrens Besch. and F. ventricosus Lesq. The peristome of F. perdecurrens is described for the first time. Key words: aquatic mosses, Asia, California, Europe, Fissidens grandifrons, F. perdecurrens, F. ventricosus, North America, perichaetia, perigonia, peristome, rarity of sporophytes, rheophytes Ronald A. Pursell, Department of Biology, 208 Mueller Laboratory, The Pennsylvania State University, University Park, PA 16802, U.S.A.; e-mail: [email protected] James R. Shevock, California Academy of Sciences, 55 Music Concourse Drive, Golden Gate Park, San Francisco, CA 94118, U.S.A. INT R ODUCT I ON Fissidens grandifrons Brid. [subg. Pachyfissidens Taiwan, Pakistan, the western Himalayas, southern (Müll. Hal.) Kindb. sect. Pachyfissidens (Pursell India, and Siberia. Throughout the range of the & Bruggeman-Nannenga 2004)] is a large and species, however, sporophytes are rare, and have conspicuous aquatic species found principally been described and illustrated only from collec- in streams and springs of limestone geology or tions from Asia, the probable center of distribution aquatic systems with concentrations of calcium for the species. It is remarkable that a species with ions. The species has a circumpolar distribution such limited sporophyte production and no known in North America, Europe, and Asia. In eastern gemmae has attained such a broad distribution. North America the species ranges from Ontario Hill (1902), however, maintained that the species in Canada into the adjacent states Michigan and spreads by radiculose branches that are easily Wisconsin of the United States, and, south into detached in rapidly running streams. When en- the states of Alabama, Kentucky, Tennessee, Mis- countered, populations can be extensive, forming souri, and Arkansas. In western North America the large, robust colonies. Recent collections by the species extends from British Columbia in Canada second author in which perigonia were found in south into the states of Washington, Oregon, a California collection, and perichaetia and sporo- California, Nevada, Idaho, Montana, Utah, Wyo- phytes were found in a China collection prompted ming, and Arizona and also Mexico. In Europe a survey of the holdings of this species in MO to F. grandifrons is found in the Pyrenees mountains determine if these structures were present in other of southwestern France and northeastern Spain, collections of the species. The purposes of this southeastern Germany, north central Switzerland, paper are to report the finding of sporophytes in and the Caucasus of southern Russia. In Asia, the a collection from China; the finding of perigonial species occurs in Japan, China, northern Vietnam, and perichaetial plants; to describe and illustrate the perigonia and to describe the perichaetia; to 1 Corresponding author propose a possible explanation for the rarity of 476 POLISH BOTANICAL JOURNAL 58(2). 2013 sporophytes; to compare the sexual reproduction of AMERICA. U.S.A. CAL I FO R N I A . Plumas Co.: Koch F. grandifrons with that of other dioicous aquatic 1893. MI CH I GAN . Mecosta Co.: Smith B734. MI SSOU ri . to rheophytic species of Fissidens, and to describe Carter Co.: Haggerty 2; Shannon Co.: Redfearn et al. the peristome of F. perdecurrens Besch. 703. CANADA. ONTA ri O . Bruce Co.: Ireland 20598; Grey Co.: Mixley s.n., 7 July 1971. – ASIA. CH I NA . Sichuan Province: Shevock 36240. SP O R O P HYTES OF FISSIDENS GRANDI F RONS Both perigonial and perichaetial plants are pro- IN CH I NA duced in Fissidens grandifrons, although never in Only three collections of Fissidens grandifrons great numbers and not in the same mat. Both types with sporophytes have been reported previously of plants are present in North America. However, in the literature: TAIWAN, Lin 8699 (Li 1985; perigonial plants were not found among those Pursell 2007), Lin 12831 (Iwatsuki & Suzuki, collections from Asia with sporophytes. Interest- 1982; Pursell 2007); PAKISTAN, Higuchi 20161 ingly, only perigonial plants were seen in Euro- (Pursell, 2007). These collections are in NICH. pean collections. The latter, however, may be due The second author found immature sporophytes to the small sample (three collections). In North from the following site in China: SI CHUAN PR OV - American specimens, gametangia are present from I NCE . MUL I CO : Hengduan Mts., ca 10 km N of the the later part of June through mid-August. This is city of Muli, 28°00′32.3″N, 101°12′38.0″E, elev. also the case for the collection from France, but in 2550 m [ca 8366 ft], on vertical wall of a road bank the collections from Germany and Spain, perigonia with dripping water, Shevock 36240 (MO). are present on the plants in February. Sporophytes of Fissidens grandifrons are indeed rare. The MO holdings of the species DESC rip T I ON OF THE P E ri GON I UM (including the one listed above) total 362 collec- Perigonial branches develop primarily on the out- tions. Iwatsuki and Suzuki (1982) examined 91 ermost stems of a mat. They are acropetalous in de- specimens from Japan, giving a grand total of 453 velopment and occur in rows in the axils of leaves collections of which approximately 0.009% had on both sides of the upper one-third of a stem, sporophytes. but they can also occur further down on the stem and in the axils of leaves of branches of the pri- PE ri GON I A AND P E ri CHAET I A IN FISSIDENS mary stem. Mature perigonial branches protrude GRANDI F RONS from the leaves and are easily seen. At maturity, a perigonial branch is ca 2 mm long and consists Fissidens grandifrons is a species that once recog- of a short stem with lateral or basal rhizoids, and nized is probably not further examined in detail. the perigonium (Fig. 1). Two perigonial branches However, a close examination of the holdings are usually present in each axil; the second branch of the specimens in MO has resulted in finding originating from a small lower leaf on the stem of 11 collections (0.03%) with either perigonial or the primary perigonial branch (Fig. 1). The ma- perichaetial plants. Unfortunately, Iwatsuki and ture perigonial branches can easily detach from Suzuki (1982) did not record Japanese collections the parent stem or branch or be tightly attached. seen with perigonia or perichaetia. Usually four pairs of leaves make up a perigo- SP EC I MENS EXAM I NED wi TH P E ri GON I A : NORTH nium, the lowest pair is very small, ecostate or AMERICA. U.S.A. CAL I FO R N I A . Siskyou Co.: Shevock nearly so, and either rounded or obtuse. Each of 40560. CANADA . British Columbia: Queen Charlotte Is- the remaining leaves consists of two very broad lands, Schofield 45292. – EUROPE. FR ANCE . Pyrénées- vaginant laminae, at least one of which is notched Orientales: Husnot, Musci Galliae 163. GE R MANY . at the place where it joins the proboscis i.e., costa Rheinland: Frahm 11361. SP A I N . Huesca: Granzow de and very narrow dorsal and ventral laminae. The la Certa 2245. largest leaf is ca 1 mm long. All laminae are unis- SP EC I MENS EXAM I NED wi TH P E ri CHAET I A : NORTH tratose. Juxtacostally in the vaginant laminae there R. A. PURSELL & J. R. SHEVOCK: FISSIDENS GRANDIFRONS 477 Fig. 1. Fissidens grandifrons Brid. Two perigonial branches from a leaf axil on the parent stem. Lowermost leaf is small and ecostate (from Husnot, Musci Galliae 163). is a broad area of large, oblong, nearly hyaline six, the largest of which is ca 60 µm long. Para- cells (few chloroplasts) bordered by a broad area physes are absent. of small, mostly quadrate, chlorophyllose cells The presence of two perigonial branches (Fig. 2). Together, the two uppermost and largest present in the axil of a leaf is probably a rare perigonial leaves form a cup that envelopes the condition among aquatic Fissidens. Loosely at- very short stalked antheridia that number around tached perigonial branches were found in Shevock Fig. 2. Fissidens grandifrons Brid. Single perigonial leaf showing the enlarged area of translucent cells (from Frahm 11361). 478 POLISH BOTANICAL JOURNAL 58(2). 2013 40560 from California, while in all three of the upstream to perichaetial plants, and the water flow collections from Europe they tightly adhered to strong enough to dislodge the loosely attached per- the stem. This perhaps indicates that at maturity igonial branches and transport them to the exserted the entire perigonial branch is detached or only perichaetial branches firmly attached to the parent the mature sperms are released. stems. Or, in the case when the perigonial branches are not detached, the sperm must be carried to the DESC rip T I ON OF THE P E ri CHAET I UM perichaetial plants. This probably does not occur Perichaetial branches, like perigonial branches, are in plants in rapidly running streams but rather in found on the outermost stems of a mat, but are less those found along banks, in dripping water sites, or numerous. Like perigonial branches, the pericha- in splash zones where those collections with sporo- etial branches occur in the axils of leaves in the phytes or either perichaetial or perigonial branches upper one-third or lower of the parent stem where have been documented.