Title: Contributions from the Botanical Laboratory, vol. 7
Identifier: contributionsfro07univ (find matches)
Year: 1892 (1890s)
Authors: University of Pennsylvania. Botanical Laboratory
Subjects: Botany; Botany
Publisher: Philadelphia : University of Pennsylvania Press
Contributing Library: Penn State University
Digitizing Sponsor: Lyrasis Members and Sloan Foundation

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' 'â > li ^1 ^11 660 AMERICAN JOURNAL OF BOTANY (Vol. i6. Actinothamnion antillanim sp. nov. W. R. Taylor.âPlant filamentous, soft and delicate, the main axis sparingly branched, uncorticated, its basal part repent to ascending, at some nodes bearing branches which divide into an erect vegetative ramulus and a descending branched hapteron, at other nodes bearing only the erect ramulus; erect axes continuations of, or branches from, the basal part, ascending to completely free, often with haptera below for attachment to neighboring algae, i-2 cm. tall or possibly more, rarely or sparingly divided into similar branches; all portions spirally beset with'alternate spreading ramuli 5-(/o)-i5 cells long, which bear single or to 3 whorled projecting cells at each of the upper nodes; indetermmate branches of the axis formed somewhat below the top of the supporting cell, like the primary axis dividing by slightly oblique segments from the broader side of each of which is developed a new branch or a ramulus, the initial cell of which seems generally to be cut off from the main axis as early as the second segment behind the apex; ramuli differing from the axes in their continuing development in that segmentation of the primary cell row is by transverse walls, followed by strongly oblique walls which determine the whorled projecting cells, the apical cell of the ramuli at first 2-3 times as long as broad, later shorter than broad and finally converted into i or a whorl of 3 terminal cells; basal portion of axis of filaments 32-48 fi in diameter, cells 95-420 M long, slightly swollen at the nodes, lateral membrane 5-7-9-5 M thick, chromatophores sublinear, straight to somewhat flexuous, approxi- mately 2 M broad; erect portion of axis of filaments about 40 m in diameter near the base, 20 m in diameter near the apical tuft, sometimes slightly larger, to 47 /x, in the middle portion, cells 45-60 m long near the apical tuft, 380-420 M long near the base; membrane 4-8 m thick, chromatophores sub- linear; hapteral branches 1-3 cells long in the shaft, often bearing i erect vegetative ramulus or occasionally an erect indeterminate axis, the attaching portion few-several divided into unguicular segments; whorled projecting cells formed in successive vertical series, the first produced being the dorsal ones upon the outer sides of the usually somewhat arcuate young ramuli, followed by i or more series, the third series usually completed upon a few nodes only; ramuli of mature condition (not from the immediate tip region nor the basal parts), showing a lower shaft portion 13-17 M in diameter, the basal cell shorter to equalling the diameter in length, the second and higher successively longer in approaching the general shape, in the middle portion the ramulus 13-19 m in diameter (excluding the whorled cells), cells 38- 60 II long, in the upper portion cells 13-19 M in diameter and 10-30 /x long, lateral membrane of cells thicker to 3-5-4-0 M in the contracted basal portion where the cell junction angles are rounded internally, but toward the tip portion 1.5-2.0 m and fairly uniform, chromatophores round to oval; whorled projections unicellular, 1-3 at a node, usually an equal-angled tri- farious whorl in the upper middle portion of each ramulus, (where only 2 cells are present these either diametrically opposite as is usual below or displaced as if to accomodate the third (absent) member of a whorl, as near or above the region of 3-celled whorls) length 6-11 m, diameter 5.5-7-5 M» ovoid-conical, membrane about 1.5 m thick, chromatophores round to oval, closely-packed; caducous ramuli or colorless hairs absent; reproductive organs not seen. Among Ileterosiphonia, Griffithsia, Crouania, and other minute algae on dead Gorgonians; Baie Anglais, Aquin, Haiti; collected by C. H. Arndt, April 3, 1927. Material deposited in the New York Botanical Garden herbarium and retained in the collections of the describer. Nov.. 1929) TAYLOR AND ARXDT â ALGAE OF HISPAXIOLA 661
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Text Figs. 7-10. Actinothamnion antillarum. In Fig. 7 appears a habit sketch. Fig. 8 illustrates the initial of a lateral hapteral branch with an erect determinate branchlet Fig. 9 shows a completely developed hapteral branch. Fig. 10 shows the basal portions of determinate branches from the lower part of the plant. All X 150.

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