ULTRASTRUCTURE OF MEIOSIS IN DASYA BAILLOUVIANA (RHODOPHYTA). II. PROMETAPHASE I—TELOPHASE II AND POST-DIVISION NUCLEAR BEHAVIOR1

This is the second of two papers which together are the first comprehensive ultrastructural report of meiosis in a red alga. Many details of the meiotic process in Dasya baillouviana (Gmelin) Montagne are the same as those reported previously for mitotic cells in ceramialian red algae, but several characteristics seem unique to meiotic cells. The nucleus and nucleolus of meiotic cells are larger than those of mitotic cells and large accumulations of smooth ER are often found at the division poles during meiosis 1. The function of the ER accumulations is unknown. Importantly, both interkinesis and a simultaneous division of two separate nuclei during meiosis II was demonstrated. These new observations fail to support earlier speculation on higher red algae for a “uninuclear” meiosis (both nuclear divisions within the same nuclear envelope). However, following meiosis II the four nuclei migrate centripetally and possibly fuse in the center of the tetrasporangium. This post-division nuclear maneuvering is not understood, but our interpretation accounts for the earlier and erroneous impression of “uninuclear” meiosis. Perhaps the most important aspect of meiosis observed in Dasya is its basic adherence to the pattern commonly seen in higher plants and animals. This conservatism of the meiotic process lends further skepticism to the belief that red algae are extremely “primitive” organisms, although they undoubtedly represent a very “ancient” group of eukaryotic plants.     

ULTRASTRUCTURE OF AUXILIARY AND GONIMOBLAST CELLS DURING CARPOSPOROPHYTE DEVELOPMENT IN FAUCHEOCOLAX ATTENUATA (RHODOPHYTA)1

The ultra structure of post-fertilization development in Faucheocolax attenuata Setch. is described. Following fertilization and transfer of the diploid nucleus to the auxiliary cell, four gonimoblast initials usually are produced of the multinucleate auxiliary cell. Gonimoblast initials originally are uninucleate but undergo karyokinesis to form multinudeate gonimoblast cells. Terminal or generative gonimoblast cells cleave successively to form lobes of incipient carpospores, with each group of spores differentiating synchronously. Portions of the initial generative gonimoblast cells, however, remain to resume karyokinesis and repeat the process of cleavage into carpospores. Axial gonimoblast cells are transformed into secretory cells, which produce mucilage. Generative gonimoblast cells and auxiliary cells are similar in cellular structure. Both contain typical red algal proplastids, some dictyosomes, cytoplasmic concentric membranes, and numerous small vesicles. In addition, dark staining spherical masses, occurring in the cytoplasm of all cell types, may represent dehydrated haploid chromatin. Large septal plugs interconnect gonimoblast cells and the auxiliary cell. These plugs are small when first formed but increase dramatically in size during carposporophyte development.     

ULTRASTRUCTURE OF TETRASPOROGENESIS IN THE CORALLINE ALGA HALIPTILON CUVIERI(RHODOPHYTA)1

Tetrasporogenesis begins with the formation of the tetra-sporocyte, an elongate, apparently wall-less, cell containing few organelles. The tetrasporocyte rapidly elongates and a distinctive cell wall forms before the onset of meiosis. During this elongation phase there is also an increase in the number of plastids and mitochondria. The meiotic tetrasporocyte is characterized by extensive development of perinuclear endoplasmic reticulum (PNER) and peripheral endoplasmic reticulum (PER) and during the latter stages of sporogenesis by internuclear endoplasmic reticulum. Immediately next to the nuclear envelope the inter-cisternal spaces of the PNER are filled with very electron dense material and the PNER cisternae are quite narrow, while further away from the nucleus the PNER cisternae dilate. Throughout meiosis there is continued replication of plastids and mitochondria as well as synthesis of starch and the formation of Golgi-derived vesicles with very osmiophilic contents. Cytokinesis begins with the formation of striated thickenings on the inside of the tetrasporocyte wall, at the sites where the cleavage furrow, produced by infurrowing of the plasmalemma, will be formed. Early in cytokinesis the PER disappears and is replaced by osmiophilic vesicles and mitochondria. Tubular plasmalemma invaginations of 27–30 nm width also appear during the early stages of tetraspore wall formation. The ultra-structure of the early stages of tetraspore germination is also described.     

PARASITIC INTERACTIONS AND VEGETATIVE ULTRASTRUCTURE OF CHOREOAEMA THURETII (CORALLINALES,RHODOPHYTA)1

The monotypic coralline red alga, Choreonema thuretii (Bornet) Schmitz (Choreonematoideae), grows endophytically within three geniculate genera of the Corallinoideae. Although the thallus of Choreonema is reduced, lacks differentiated plastids, and is endophytic except for its conceptacles, its status as a parasite has been questioned because cellular connections to the host had not been ob served. Transmission electron microscopy, however, disclosed a previously undescribed type of parasitic interaction in which Choreonema interacts with its host through specialized cells known as lenticular cells. These small, lens-shaped cells are produced from the single file of host-penetrating vegetative cells. Pit plug morphology between vegetative and lenticular cells is polarized. Plug caps facing the vegetative cell have normal coralline morphology, while those facing the lenticular cell are composed of three layers. Regions of lenticular cells near host cells protrude toward the host cell; upon encountering the host cell wall, the prolrusion produces numerous finger-like fimbriate processes that make cellular connections with the host cell. Lenticular cells may extend several protrusions toward a host cell or penetrate more than one host cell; two or more lenticular cells may also penetrate the same host cell. The lack of secondary pit connections, cell fusions, and passage of parasitic nuclei suggest that this parasitic relationship may be evolutionarily older than previously reported cases of parasitism in red algae.     

DASYA ROSLYNIAE SP. NOV. (DASYACEAE,RHODOPHYTA), WITH A DISCUSSION ON GENERIC DISTINCTIONS AMONG DASYA,EUPOGODON, RHODOPTILUM,AND POGONOPHORELLA1

Dasya roslyniae sp. nov. (Dasyaceae, Rhodophyta) is described from subtidal habitats at Split Solitary Island (30°14′S, 153°11′E), New South Wales, Australia. The new species is distinct within the genus due to its strongly compressed and secondarily bilaterally branched axes, differing from the majority of Dasya species that are terete and secondarily radially organized. Pseudolaterals are quickly caducous on ventral and dorsal (transverse) surfaces but are persistent on lateral surfaces for short distances from the apex, leaving the bulk of the plants flattened and denuded. Its gross morphological characters are thus similar to those displayed by the genera Pogonophorella, Eupogodon (formerly known as Dasyopsis), and Rhodoptilum. Characters used for separating these genera and Dasya are, in some cases, overlapping and in need of critical evaluation. To the primarily radially organized taxa, determined by examination of divisions of the apical cell, are placed species of Dasya, six species now included in Eupogodon, and the type and only species of Pogonophorella californica. Examination of the activity of the apical cells of Eupogodon planum and Rhodoptilum plumosum, the type species of their genera, confirms the primary bilaterality of these two genera, and the traditional defining feature of Eupogodon (lack of discernible pericentral cells in cross-section of indeterminate axes) is shown to be untenable. A secondary character that would separate Eupogodon and Rhodoptilum is the polysiphonous bases of otherwise monosiphonous laterals (pseudolaterals) in Eupogodon and the monosiphonous bases in Rhodoptilum.     

ULTRASTRUCTURE OF CELL DIVISION AND REPRODUCTIVE DIFFERENTIATION OF MALE PLANTS IN THE FLORIDEOPHYCEAE (RHODOPHYTA): CELL DIVISION IN POLYSIPHONIA1

Cell division in the marine red algae Polysiphonia harveyi Bailey and P. denudata (Dillwyn) Kutzing was studied with the electron microscope. Cells comprising the compact spermatangial branches of male plants were used exclusively because of their small size, large numbers and the ease with which the division planes can be predetermined. Some features characterizing mitosis in Polysiphonia confirm earlier electron microscope observations in Membranoptera, the only other florideophycean algae in which mitosis has been studied in detail. Common to both genera are a closed, fenestrated spindle, perinuclear endoplasmic reticulum, a typical metaphase plate arrangement of chromosomes, conspicuous, layered kinetochores, chromosomal and non-chromosomal microtubules, and nucleus associated organelles (NAOs) known as polar rings (PRs) located singly in large ribosome-free zones of exclusion at division poles in late prophase. However, other features, unreported in Membranoptera, were observed consistently in Polysiphonia. These include the presence of PR pairs in interphase-early prophase cells, the attachment of PRs to the nuclear envelope during all mitotic stages, the migration of a single PR to establish the division axis, a prominent, nuclear envelope protrusion (NEP) at both division poles at late prophase, the prometaphase splitting of PRs into proximal and distal portions, and the reformation of post-mitotic nuclei by the separation of an elongated interzonal nuclear midpiece at telophase. During cytokinesis, cleavage furrows impinge upon a central vacuolar region located between the two nuclei and eventually pit connections are formed in a manner basically similar to that reported for other red algae. Diagrammatic sequences of proposed PR behavior during mitosis are presented which can account for events known to occur during cell division in Polysiphonia. Mitosis is compared with that reported in several other lower plants and it is suggested that features of cell division are useful criteria to aid in the assessment of phylogenetic relationships of red algae.     

ULTRASTRUCTURE OF TETRASPOROGENESIS IN PALMARIA PALMATA (RHODOPHYTA)1

The tetrasporangial initial in Palmaria palmata (L.) O. Kuntze (formerly Rhodymenia palmata (L.) Greville) arises from a cortex cell which enlarges and deposits a protein-rich wall layer. This cell undergoes mitosis to form a tetrasporocyte and a stalk cell. Synaptonemal complexes are formed in the sporocyte nucleus while in the cytoplasm floridean starch is deposited in association with ER or with particles presumed to be ribosomes. Microbody-like structures become numerous between the nuclear envelope and perinuclear ER, and clusters of non-membranous, spherical structures also are associated with the nucleus. Chromatin condensation is reversed following pachytene and a prolonged diffuse stage ensues, when dictyosomes and ER produce vesicles which deposit mucilage rich in sulfated and acidic polysaccharides around the tetrasporocyte. A conspicuous lenticular thickening of the mucilage sheath develops at the apical end of the sporangium. Dictyosomes are frequently associated with mitochondria which may be associated with chloroplasts. Following nuclear divisions the tetrasporocyte is cleaved into four spores by sequentially initiated, but simultaneously completed periclinal and anticlinal furrows. When mucilage deposition ceases, the dictyosomes begin to produce vesicles with glycoprotein-rich contents. These vesicles are abundant in released tetraspores, and they probably contain adhesive material aiding in the attachment of the liberated spores.     

ULTRASTRUCTURE OF SWARMERS IN THE LAMINARIALES (PHAEOPHYCEAE). I. ZOOSPORES1

Zoospores of 17 species in 14 genera of Laminariales, collected in the northeast Pacific Ocean, were studied by electron microscopy. These zoospores are unique in the brown algae in lacking both an eyespot in the single chloroplast and any associated swelling at the base of the shorter, posterior flagellum. Spores of all species examined possess a distal whiplash portion on the longer, mastigoneme-bearing anterior flagellum. This appendage may sometimes be as long as the mastigoneme-bearing portion of the flagellum, but it is only seldom preserved in the preparations for electron microscopy. A microtubular cytoskeleton is probably responsible for maintaining the shape of the spore. It consists of a short band of about 10 microtubules between the two basal bodies, scattered tubules converging at the anterior of the spore, a band of 7–9 tubules directed anteriorly from the anterior basal body, and a band directed posteriorly from the posterior basal body. These anterior and posterior bands may form one continuous band looping around the periphery of the spore. Variation with possible taxonomic significance was found in the ultrastructure of vesicles which apparently contain adhesive material, and which are extruded through the plasmalemma when the zoospores settle.     

ULTRASTRUCTURE OF SWARMERS IN THE LAMINARIALES (PHAEOPHYCEAE). II. SPERM1

The ultrastructure of sperm from 13 species in 11 genera of Laminariales collected in the northeast Pacific Ocean is unique in the brown algae. The sperm are elongate, and possess a nucleus, several mitochondria and two or three chloroplasts, but no eyespot. The anterior flagellum bears mastigonemes on the proximal half of its length; a distal “whiplash” portion lacks mastigonemes and is an extension of only the two central singlet microtubules of the axoneme. A peculiar feature of these sperm is the posterior flagellum, which is longer than the anterior flagellum and tapers distally as the doublet microtubules become singlets and decrease in number. This feature contrasts with the laminarialean zoospore, which possesses a short posterior flagellum with the usual “9 + 2” axoneme. The structure of these sperm differs from that reported for Chorda, the sperm of which resembles a primitive brown algal zoospore. The facts support the concept that Chorda is the most primitive member of the Laminariales.     

ULTRASTRUCTURE OF THE CORALLINACEAE (RHODOPHYTA) II. VEGETATIVE CELLS OF LITHOTHRIX ASPERGILLUM1

The ultrastructure of the calcareous red coralline alga Lithothrix aspergillum Gray and the development of the various tissue types has been studied. The sub-apical meristematic tissue alternately produces genicular or intergenicular cells. The genicular cells rapidly elongate and their cell walls thicken and become denser as more fibrillar wall material is laid down within the cell wall. These cells contain little cytoplasm and few organelles. The inter genicular cells which elongate only slightly during development have a small vacuole and many free starch grains in the cytoplasm. The peripheral cells in each inter genicular layer remain meristematic and form a cortical cell layer over the genicular cells. These cortical cells and the apical meristematic cells are covered by small epidermal cells which have extensive cell wall ingrowths between the chloroplasts. The inter genicular cells are calcified. Although the CaCO₃ is laid down within the cell walls, there is always a thin layer of CaCO₃-free organic cell wall material between the plasmalemma and the CaCO₃ impregnated wall. Only the distal tips of the genicular cells are calcified. In old genicular tissues of Lithothrix, secondary deposits of CaCO₃ of unknown crystallography are also found in the spaces between the cell walls. Thus there appear to be at least two mechanisms of calcification in this alga.     

MEIOSIS,BLADE DEVELOPMENT,AND SEX DETERMINATION IN PORPHYRA PURPUREA (RHODOPHYTA)1

The discovery in the early 1980s that meiosis occurs during germination of conchospores of Porphyra yezoensis Ueda suggested that the sexually divided fronds of Porphyra purpurea (Roth) C. Agardh might similarly originate from meiotic segregation of a pair of sex-determining alleles during early sporeling development. After establishing conditions suitable for propagating P. purpurea in culture, observations on developing sporelings demonstrated that meiosis takes place during the first two divisions of the germinating conchospores. In the first division, the spore is split into an upper and lower cell. In the second, an anticlinal division in the upper cell yields two daughter cells situated one beside the other, and a periclinal division in the bottom cell gives two cells arranged one above the other. Thus, during normal development, the first four cells of the sporeling constitute a meiotic tetrad whose cells are arranged in a characteristic fashion. Stable color mutants of P. purpurea were isolated, genetically characterized, and used as genetic markers to follow the fate of individual cells of the tetrad during subsequent frond development. Nearly the entire blade of the mature thallus is derived from the two upper cells of the tetrad, with the two lower cells mostly giving rise to the rhizoidal holdfast region. Cell lineage boundaries laid down by the segregation of color alleles at meiosis corresponded perfectly with those later defined by sexual differentiation on the same fronds, strongly supporting the hypothesis that sex determination in P. purpurea is controlled by alleles at a segregating chromosomal locus.     

PHYCOBILIPROTEIN COMPOSITION AND CHLOROPLAST STRUCTURE IN THE FRESHWATER RED ALGA COMPSOPOGON COERULEUS (RHODOPHYTA)1

Serial sections of uncorticated axial cells of Compsopogon coeruleus revealed a single interconnected parietal chloroplast. Phycobilisomes in such chloroplasts were hemidiscoidal in shape with a broad-face diameter of ca. 25–30 nm. The molar ratio of phycobiliproteins in whole cell extracts was IPE:3PC:1APC, similar to isolated phycobilisomes. Two spectrally distinct C-phycocyanin forms (A618 nm, F648 nm and A630 nm, F652 nm) were resolved in dissociated phycobilisomes along with B-phycoerythrin and allophycocyanin.     

GROWTH AND DIFFERENTIATION OF AXIAL AND LATERAL FILAMENTS IN BATRACHOSPERMUM SIRODOTII (RHODOPHYTA)1

Development of the vegetative gametophyte of Batrachospermum sirodotii Skuja was examined with light and both transmission and scanning electron microscopy. Patterns of wall growth were followed using the Calcofluor White ST pulse-chase method. Thallus structure was analysed in terms of the pattern of development of the apical, periaxial and pleuridial initials that generate the axial and whorled lateral filaments characteristic of Batrachospermum. Apical cells of axial filaments elongate initially by tip growth with the nucleus maintaining a distal position. Nuclear division is horizontal. One daughter nucleus migrates basipetally and a thin, convoluted annular septum and perforate-occluded pit connection are then formed. Elongating axial cells subsequently extend by wall deposition at the base of the cell. Periaxial cells are initiated laterally and elongate primarily by tip growth while the nucleus remains within the axial cell. The nucleus then migrates to the boundary between the initial and the axial cell, divides, and one daughter nucleus moves into the initial and the other back into the axial cell. A slightly irregular annular septum and simple-occluded pit connection are then formed. Pleuridial cell initials begin as terminal to subterminal protuberances on periaxial or pleuridial cells. They first extend by tip growth and later by bipolar band growth. The nucleus remains within the parent cell as the pleuridial initial expands and a narrow septal ring is formed between the two cells. It then migrates through the septal ring into the initial and divides transversely. One nucleus passes back into the parent cell and a thick, flat septum and perforate-occluded pit connection are formed. It is concluded that the potentially indeterminate axial filaments and the determinate lateral pleuridia represent distinct developmental types in Batrachospermum.     

STUDIES ON DEVELOPING AND RELEASED SPERMATIA IN THE RED ALGA,TIFFANIELLA SNYDERAE (RHODOPHYTA)1

Developing and released spermatia of the red alga, Tiffaniella snyderae (Farl.) Abb. were studied. Spermatia were observed under hydrodynamically defined conditions and found to be released from the exposed spermatangial heads in a spermatium-plus-strand unit that remained connected to the spermatangial head. Interactions of single-spermatial strands resulted in the formation of multi-spermatial strands as long as 600 μm with as many as 47 spermatia along their length; however, most were 100–200 μm with 8–21 spermatia. Strand length and number of spermatia were correlated. Spermatial strands contracted or extended and rotated as the water velocity past the plant was changed, and in still water the strands retracted into a clump on the spermatangial head surface. Each strand type exhibited a characteristic threshold water velocity at which it reached maximum length, and above which it broke and was carried away. Fluorescence microscopy showed that the strands did not contain nucleic acid (DNA) and could thus be differentiated from filamentous blue-green algal and bacterial epiphytes. Histochemical staining indicated that the strands and spermatial vesicles contained an acidic, sulfated polysaccharide. Chelation of Ca²⁺ with EGTA resulted in strand breakdown suggesting that this divalent cation may be involved in strand integrity. Scanning electron microscopy revealed that release from the spermatangia occurred through tears in the cuticle covering the spermatangial head if it was still present, or from exposed spermatangia. Individual spermatia were attached tangentially to a well-defined strand 0.64 μm in diameter in the contracted state to 0.2 μm in the extended state. Transmission electron microscopy of spermatangial heads showed that immature spermatangia were characterized by a centrally positioned nucleus and abundant ER cisternae filled with a moderately electron dense granular material. Later in development the spermatangia acquire two spermatial vesicles containing highly convoluted fibrillar contents. The cell becomes polarized with the nucleus displaced apically and the spermatial vesicles occupying the basal half of the spermatangium. At maturity one of the vesicles is released basally. Liberated spermatia contain a membrane-bound nucleus and mitochondria and are associated with an oblong accumulation of fibrous material similar in size and position to the strand observed with the SEM. These strands are discussed in relation to red algal fertilization and other phases of the red algal life-history.     

ULTRASTRUCTURE AND CYTOCHEMISTRY OF EARLY SPERMATANGIAL DEVELOPMENT IN ANTITHAMNION NIPPONICUM (CERAMIACEAE,RHODOPHYTA)1

Spermatial development and differentiation of wall components were investigated by electron microscopy and cytochemical methods in Antithamnion nipponicum Yamada et Inagaki. The spermatium is composed of two parts, a globular head and two appendages projecting from near the basal portion. The appendages originate form spermatangial vesicles (SVs) and follow a developmental sequence beginning as amorphous material and ending as fully formed fibrous structures compressed with in the SVs. SV formation is due to contributions initially from endoplasmic reticulum and later form dictyosome-derived vesicles. Chemical differentiation of the spermatial wall occurs early in its development. Calcofluor white ST does not label spermatial walls, indicating an absence of cellulose polysaccharides, which are abundant in vegetative cell walls. Labeled lectins show that α-d -methyl manose and / or α-d -glucose as well as N-acetyl-glucosamine, β-d -galactose, and α-l -fucose moieties are present on the spermatial wall but not in the vegetative cell wall. The glyconjugate with α-d -methyl mannose and / or glucose residues, previously reported as a gamete recognition molecule in this species, is distributed along the surface of spermatia as well as in the SV during spermatangial development.     

THE MORPHOLOGY AND DEVELOPMENT OF SOME PROMINENTLY STALKED SOUTHERN AUSTRALIAN HALYMENIACEAE (CRYPTONEMIALES,RHODOPHYTA). I. CRYPTONEMIA KALLYMENIOIDES (HARVEY) KRAFT COMB. NOV. AND C. UNDULATA SONDER1

Several southern Australian red algae of the family Halymeniaceae (Cryptonemiales) are differentiated into hard, massive stalks and considerably softer laminar blades or phyllodes. The taxonomy, morphology and pit-connection ultrastructure of one such species, Cryptonemia kallymenioides (Harvey) Kraft comb. nov., are compared to C. undulata Sonder, which lacks massive stalks. In both species there is extensive periodic secondary cortication of the stalks, resulting in the formation of distinct “growth rings.” The blades of C. kallymenioides appear to be seasonal and its stalks perennial, while plants of C. undulata are apparently perennial but shorter lived than C. kallymenioides. As a result, stalks in the latter can reach 2–3 cm in diameter with up to 18 growth rings, compared to the 1–2 mm diameters and up to 6 rings within the stalks of C. undulata. Heavy secondary thickening of cortical cell walls occurs in both species and confers a “woody” texture to the stalks of C. kallymeniodes. Regardless of the large differences in average stalk diameters between the two species, the pit-connection ultrastructure from cortex to medulla shows much the same sequence of morphological modification. Pit-connections are standard red algal structures in the outer cortex, but become increasingly convoluted on the membrane-bound surfaces abutting cytoplasm and develop wider apertures and less dense cores with increasing distance from the stalk surface. In occasional medullary cells of C. kallymenioides, the cytoplasm disintegrates, leaving cell walls and pit-connections to play an apparently structural role which has not been reported in other red algae. It is suggested that the increase in aperture size and surface areas of pit-connections is compatible with their playing a role in the intercellular transport of solutes towards the inner cell layers which may, in C. kallymenioides, lie many millimeters distant.     

BATRACHOSPERMUM HETEROCORTICUM SP. NOV. AND POLYSIPHONIA SUBTILISSIMA (RHODOPHYTA) FROM FLORIDA SPRING-FED STREAMS1

Polysiphonia subtilissima Mont. Is reported for the first time from a freshwater environment. The presence of four pericentral cells, subdichotomous branching, apical trichoblasts and rhizoids arising from pericentral cells combined with a lack of cortication and reproductive cells is consistent with marine populations of this species. The range of filament length is 1.4–4.7 cm. Branch diameters are 38–76 μm and pericentral cell lengths are 58–125 μm. Batrachospermum heterocorticum sp. nov. is distinguished primarily by a developmental change in cortical filaments from typical cylindrical cells (5.0–7.9 μm diam in initial stages to enlarged, elliptical cells (12.9–24.1 μm diam) in mature axes. Another unique feature of this species is carpogonia with cylindrical, pedicellate trichogynes on stringht carpogonial branches in mid to outer portions of lateral whorls. Other characteristics of B. heterocorticum include the following: olive-green color, 2–6 cm length, dichotomous to trichotomous fascicles in 4–7 tiers, 385–647 μm whorl diameters, 109–198 μm carpospore diameters and relatively small “chantransia” filaments.     

LIFE HISTORY AND GROWTH OF LAURENCIA BRACHYCLADOS (RHODOPHYTA,CERAMIALES)1

Laurencia brachyclados Pilger from Hawai'i completed a “Polysiphonia-type” tri-phasic life history in 21 weeks in laboratory culture. Tetraspores developed into gametophytes in a nearly 1:1:1 ratio of females: males: non-reproductive. Carpospores were released as early as 21 days after mixing virgin female and male gametophytes. Cultured thalli showed a “guerilla type” growth form. Other Hawaiian Laurencia species in culture had longer maturation times or remained non-reproductive. Variation in life history schedules may influence Laurencia species coexistence and algal community structure.