Botanical Gazette/V40/A New Genus of Ophioglossaceae
| A NEW GENUS OF OPHIOGLOSSACEAE |
| (WITH ONE FIGURE) |
During the spring of 1903 the writer discovered the gametophytes of Botrychium obliquum Muhl., and later announced the fact in a catalogue of the pteridophytes of Minnesota.[1] Since that time both sporophyte and gametophyte of this and other species of Botrychium have been subjected to careful study. The gametophytes of Botrychium virginianum have been found in large numbers, and a few gametophytes of B. simplex and B. matricariaefolium were found in 1904.
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| Fig. 1. — Photomicrograph of a section through a gametophyte and young sporophyte of Sceptridium obliquum. The section is vertical, and transverse of the gametophyte. The root is already protruded from the under side of the gametophyte, while the position of the first leaf was marked by a pronounced elevation on the upper side. a, archegonium; s, suspensor; t, stem tip; l, first leaf; r, root. × 60. |
While the results of the investigation are not ready for final publication, it seems at the present time desirable to call attention to the embryo of Botrychium obliquum, as it affords evidence bearing on a question now being agitated by others. In two recent papers Campbell[2] has disputed Bower's contention that the Ophioglossaceae are allied to the Lycopodiales. Campbell would derive them directly from the Bryophyta.
The gametophytes of Botrychium obliquum are subterranean and destitute of chlorophyll. They grow by a distinct apical meristem, are flattened dorsiventrally, and possess many long rhizoids. They are monoecious. The reproductive organs are developed on the flattened dorsal side and in their organization differ essentially from those of the Botrychium virginianum as described by Jeffrey.[3]
The oosperm upon segmentation does not develop directly into a spherical protocorm, as is the case in all other ferns which have been studied, but first gives rise to a long suspensor, which burrows into the tissue of the gametophyte in the manner characteristic of certain lycopod embryos. At the tip of this suspensor a spherical protocorm is organized, out of which the stem and root apices are shortly differentiated. The axis of the metacorm transfixes the protocorm and all the tissue of the latter, except the suspensor, becomes a permanent part of the metacorm. The embryo does not, therefore, possess a lateral cotyledon (nursing-foot) as does Botrychium virginianum. The root grows downward and emerges from the under side of the gametophyte, and at a later period the first leaf breaks through the upper surface. The relation of the members in the young embryo and its orientation in the gametophyte are well illustrated by the accompanying figure.
A study of the mature sporophytes of the ternate species of Botrychium discloses unique characters which alone mark them as a natural group entitled to generic rank. Considering, in addition, the anomalous character of their embryos as illustrated by Botrychium obliquum, it appears at once desirable to segregate them as a distinct genus.
The writer would therefore suggest the name Sceptridium (from σκήπτν), in allusion to the scepter-like sporangiophore.
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[edit]SCEPTRIDIUM, a new genus of Ophioglossaceae.
Stem subterranean, short, erect, with many clustered roots. Sporophyll dividing near the stem into a long petioled sporangiophore and a shorter petioled sterile segment. Sporangiophore erect, bi-, tri-, or even quadripinnate, bearing naked, spherical sporangia in two rows. Sterile segment inserted obliquely near or at the surface of the ground, ternately divided or compound. Gametophyte tuberous, subterranean, saprophytic, monoecious. Embryo with a suspensor and without a pronounced lateral cotyledon; its axis straight, the root emerging from the lower side of the gametophyte.
To this genus should be referred the following described but ill-defined species and varieties:
Sceptridium australe (R. Br.). —
Botrychium australe R. Br., Prodr. Fl. Nov. Holl. 164. 1810.
Sceptridium biforme (Colenso). —
Botrychium biforme Colenso, Trans. New Zeal. Inst. 18 : 223. 1886.
Sceptridium biturnatum (Lam.). —
Osmunda biternata Lam., Encyc. Meth. Bot. 4 : 650. 1797.
Botrychium biternatum (Lam.) Underw., Bot. Gazette 22 : 407. 1896.
Sceptridium californicum (Underw.). —
Botrychium californium Underw., Torreya 5 : 107. 1905.
Sceptridium Coulteri (Underw.). —
Botrychium Coulteri Underw., Bull. Torr. Bot. Club 5 : 537. 1898.
Sceptridium daucifolium (Hook. & Grev.). —
Botrychium daucifolium Hook. & Grev., Ic. Fil. 2 : pl. 161. 1831.
Sceptridium decompositum (Mart. & Gal.). —
Botrychium decompositum Mart. & Gal., Mem. Acad. Sci. Bruxelles 15 : —(15). pl. 1. 1842.
Sceptridium dissectum (Spreng.). —
Botrychium dissectum Spreng. Anleit. 3 : 172. 1804.
Sceptridium Japonicum (Prantl). —
Botrychium daucifolium β japonicum Prantl, Jahrb. Bot. Gartens Berlin 3 : 340. 1884.
Botrychium japoncum (Prantl) Underw., Bull. Torr. Bot. Club 5 : 538. 1898.
Sceptridium Jenmani (Underw.). —
Botrychium Jenmani Underw., Fern Bull. 8 : 59. 1900.
Sceptridium matricariae (Schrank). —
Osmunda matricariae Schrank, Baier. Fl. 2 : 419. 1789.
Botrychium malricariae (Schrank) Spreng., Syst. Veg. 4 : 23. 1827.
Sceptridium obliquum (Muhl.). —
Botrychium obliquum Muhl., Willd. Sp. Pl. 5 : 62. 1810.
Sceptridium obliquum elongatum (Gilbert & Haberer). —
Botrychium obliquum elongatum Gilbert & Haberer, Fern Bull. 11 : 89. 1903.
Sceptridium obliquum Habereri (Gilbert). —
Botrychium obliquum Habereri Gilbert, Fern Bull. 11 : 88. 1903.
Sceptridium obliquum intermedium (Underw.). —
Botrychium obliquum intermedium Underw., Our Native Ferns, ed. 6. 72. 1900.
Sceptridium obliquum oneidense (Gilbert). —
Botrychium ternatum oneidense Gilbert, Fern Bull. 9 : 27. 1901.
Sceptrldium pusillum (Underw.). —
Botrychium pusillum Underw., Bull. Torr. Bot. Club 30 : 50. 1903.
Sceptridium robustum (Rupr.). —
Botrychium rutaefolium var. robustum Rupr., Milde Nov. Act. Acad. Caes. Leop.-Carol. 26 : 763. 1858.
Botrychium robustum (Rupr.) Underw., Bull. Torr. Bot. Club 30 : 51. 1903.
Sceptridium Schaffneri (Underw.). —
Botrychium Schaffneri Underw., Bull. Torr. Bot. Club 30 : 51. 1903.
Sceptridium silaifolium (Presl). —
Botrychium silaifolium Presl, Rel. Haenk. 1 : 76. 1825.
Sceptridium subbifoliatum (Brack.). —
Botrychium subbifoliaium Brack., U. S. Expl. Exped. 16 : 317. 1854.
Sceptridium tenuifolium (Underw.). —
Botrychium tenuifolium Underw., Bull. Torr. Bot. Club 30 : 52. 1903.
Sceptridium ternatum (Thunb.). —
Osmunda ternata Thunb., Fl. Japon. 329. 1784.
Botrychium ternatum (Thunb.) Sw., Schrader's Journ. Bot. 1800² : 111. 1801.
Sceptridium Underwoodianum (Maxon). —
Botrychium Underwoodianum Maxon, Bull. Torr. Bot. Club 32 : 220. 1905.
| — Harold L. Lyon, University of Minnesota. |