Keys to Common Genera and Species of Hawaiian Chlorophyta
1 / Plants filamentous (=single or multiple rows of cells, branched or unbranched) / 21 / Plants blade-like, tube-like, and other shapes or forms; in general not filamentous / 4
2 / Filaments unbranched / 3
2 / Filaments slightly to profusely branched; plants usually in soft to stiff clumps, often floating; attachments by rhizoids frequently from basal poles of mid to lower cells, or by cluster of basal rhizoids / Cladophora(6 spp)
3 / Plants usually in erect tufts; filaments consisting of large cells between 100-600 µm in diam., nearly isodiametric; single basal cells modified for attachment / Chaetomorpha (3 spp)
3 / Plants not tufted, mostly unattached or lying loosely on mud or rocks; filaments with cells 2-4 times longer than wide; rhizoidal branchlets lacking, basal only, or along length of filament / Rhizoclonium(3 spp)
4 / Plant bodies arranged in blades or tubes / 5
4 / Plant bodies in other shapes or forms / 7
5 / Blades one or two-cells thick (a thin section should be cut with a razor blade and examined under magnification) / 6
5 / Blades (when sectioned, as above) tubular at least near the base / Enteromorpha(6 spp)
6 / Blades one-cell thick, cells in surface view sometimes aggregated into packets / Monostroma(2 spp)
6 / Blades two cells thick; cells in surface view not aggregated / Ulva(4 spp)
7 / Some portion of the plant netlike / 8
7 / Plants not netlike / 10
8 / Bulk of plants that are up to 6 cm tall clearly netlike throughout / 9
8 / Plants not more than 3 cm tall, only distal part netlike; remainder of plant with relatively conspicuous uniseriate stem-like portion / Struvea anastomosans
9 / Plants very dark emerald green, surface soft and spongy, rarely with epiphytes / Boodlea composita
9 / Plants usually medium green or bleached yellowish, surface firm, sometimes shiny; meshes of net often occluded by epiphytes / Microdictyon (2 spp)
10 / Plants not calcified / 11
10 / Plants lightly to heavily calcified / 22
11 / Erect axes connected to creeping (prostrate) axes / 12
11 / Erect axes without creeping connecting axes / 15
12 / Reproductive structures cut off from bearing branches / 13
12 / Reproductive structures produced from ordinary branches / 14
13 / Reproductive structures localized in whorled branches / Caulerpella ambigua
13 / Reproductive structures formed in gametangia / Trichosolen oahuensis
14 / 14 - Erect axes branched radially or verticillately, or appearing to be continuation of axes; terminal branches spongy, grape-like, fan-like, feather-like, zig-zag, and other shapes / Caulerpa (7 spp)
14 / Erect axes branched pinnately or to one side (secund), not further branched or elaborated / Bryopsis(2 spp)
15 / Plants unbranched, resembling small, single glass balls up to 4 cm in diam., usually under turf or in limestone / Ventricaria ventricosa
15 / Plants branched, with large, transparent cells less than 1 cm in diam / 16
16 / Cells visible without magnification, laterally cohering or arranged in irregular clumps / 17
16 / Cells not visible without magnification, arranged in intertwined tightly woven filaments showing large diameters when teased apart / 18
17 / Branching divisions irregular / 19
17 / Branching divisions regular at first in single layer, cohering cells forming a solid or hollow cushion (sometimes open) / Dictyosphaeria(2 spp)
18 / Plants often resembling asymmetric, torn paddles; surfaces woolly or felt-like, dark olive brown, never producing pinkish liquid on standing in fresh water / Avrainvillea amadelpha
18 / Plants not paddle-like, but with many different forms; surfaces velvety, sometimes bead- like; usually dark green, always producing pinkish liquid when standing in fresh water / Codium(12 spp)
19 / Branches not constricted except where attached / 20
19 / Branches constricted throughout / Chlorodesmis caespitosa
20 / Plants forming extensive erect, crisp clumps; branches and axes shaped like irregular bottles / Valonia (2 spp)
20 / Plants forming tufts or mats, the branches not like bottles / 21
21 / Plants forming erect almost crystalline tufts; branches formed by protrusions of rounded-up protoplasts from previous order; final branches radially arranged / Siphonocladus tropicus
21 / Plants forming irregular mats, usually decumbent; branches divided irregularly dichotomously, their terminal ends often producing secondary attachments to substratum / Cladophoropsis(3 spp)
22 / Plants with disc-like jointed flattened calcified segments, mostly white, with photosynthetic portion often restricted to tops of plants / Halimeda (7 spp)
22 / Plants without disc-like segments / 23
23 / Small umbrella-like plants no more than 5 mm tall, attached by siphonous stipe / Acetabularia(3 spp)
23 / Plants fan-like, small balls, or worm-like / 24
24 / Calcification restricted to walls of fan-shaped filaments and upper portion of stipe / Rhipidosiphon javensis
24 / Calcification restricted to ends of lateral branches, forming a cortical layer / 25
25 / Plants mostly white, worm-like with tufts of hairs at apices; calcification obvious except at apices / Neomeris (2 spp)
25 / Plants mostly green, surface hexagons representing ends of lateral branches that are coherent / Bornetella sphaerica
Key to the species of Cladophora
1 / Plant coarse, branching pattern conspicuous (not requiring magnification to see) / 21 / Plant soft or fine, branching pattern inconspicuous (requiring magnification to see it) / 3
2 / Plants with large cells, visible to the unaided eye, branches in fascicles / C. dotyana
2 / Plants with smaller cells, not visible to the naked eye, branches mostly on one side, at times, strongly rebranched and claw-like / C. vagabunda
3 / Plants in short tufts / 4
3 / Plants bushy or spreading, not tufted / C. sericea
4 / Tufts isolated, pale or dark green; axes and branches frequently with adventitious holdfasts / C. socialis
4 / Tufts sometimes coalescing; yellowish green to olive green, axes and branches without adventitious holdfasts, diameter of cells of second order close to that of primary axial cells / C. laetevirens
Key to the species of Chaetomorpha
1 / Filaments with distinct basal cell. longer (to 9 mm) than cells above; filaments mostly more than 400 µm wide / C. antennina1 / Filaments attached or free-floating in tufts or strands, basal cell, if present less than 1 mm long / 2
2 / Cells in upper portion 250 - 600 µm diam., tending to be isodiametric / C. aerea
2 / Cells mostly (65) 80 - 100 µm diam., tending to be longer than wide / C. capillaris
Key to the species of Rhizoclonium
1 / Cells mostly 200 - 400 µm diam.; rhizoidal branchlets frequent, non-septate or divided into 3 - 4 short cells / R. grande1 / Cells less than 100 µm diam / 2
2 / Plants in large mats or skeins, on mud or free-floating; rhizoidal branches few or lacking; filaments often less than 50 µm wide / R. riparium
2 / Plants variable in appearance and habitat; rhizoidal branchlets usually present, some rebranched; filaments often 50 - 100 µm wide / R. africanum
Key to the species of Caulerpa
1 / Erect axes and primary branches with serrate margins, simple without branchlets / C. serrulata1 / Erect axes and primary branches with numerous branchlets, often regularly arranged and with distinctive shapes, rebranched in some species / 2
2 / Branchlets with narrow stalks and broad, flared or spherical tips / 3
2 / Branchlets cylindrical, flat and curved, tapering toward tip / 4
3 / Branchlet tips globose, with constriction between inflated tip and supporting "stalk" / C. lentillifera
3 / Branchlet tips of various shape, without conspicuous constrictions between apex and "stalk" / C. racemosa
4 / Branchlets terete, evenly arranged and continuous along erect axes and primary branches / C. sertularioides
4 / Branchlets distinctly pointed at tip, compressed, or terete with successive dichotomies / 5
5 / Branchlets flattened, sickle-shaped (curved with pointed apices) , not rebranched / C. taxifolia
5 / Branchlets terete, arranged in whorls (rarely distichous) and rebranched dichotomously several times / 6
6 / Branchlets opposite (paired) or in distinct symmetrical whorls of 4 (5), uniformly broad (about ¼ to 1/3 branch diameter) for about half the length of branchlet, then successively forked with branchlets from each dichotomy narrower and tapering to tip; plants to 2 cm / C. webbiana
6 / Branchlets 2 to several, uniformly slender, in verticillate clusters along axes and branches with dimensions of successive dichotomies similar throughout; plants to 3 - 7 cm tall / C. verticillata
Key to the species of Enteromorpha
1 / Plants branched throughout, either with repeated branching and rebranching, or with profuse proliferations (mostly uniseriate of various lengths) / 21 / Plants seemingly unbranched, others branched primarily or only near the base / 4
2 / Plants typically to 4 cm high, ultimate branchlets numerous, uniseriate; cells cuboidal to rectangular / E. paradoxa
2 / Plants 5 to 40 cm high; if present, branchlets usually multiseriate / 3
3 / Cells of European specimens described as large, often to 45 - 50 µm; chloroplast occupying only part of cell with numerous pyrenoids / E. clathrata
3 / Cells of European specimens described as small, often 6 - 18 µm diam.; chloroplast occupying most of cell with single large pyrenoid / E. prolifera
4 / In surface view, cells mostly or in some areas arranged in longitudinal row ( in narrow tubes sometimes in both longitudinal and transverse directions / E. flexuosa
4 / In surface view, cells typically not in rows but arranged irregularly throughout; plants often inflated tubes of different widths / 5
5 / Upper parts of plant above stipitate base flat with cell layers united (not hollow), or remaining free along entire or a portion of margin / E. linza
5 / Plant with no stipe, or insignificant stipe; tube not united anywhere; tubular throughout / E. intestinalis
Key to the species of Ulva
1 / Plants reticulate, netlike nature obscuring blade, mostly unattached entangled with other algae / U. reticulata1 / Plants not reticulate, clearly blade like, mostly attached / 2
2 / Individual plants with conspicuous narrow segments / 3
2 / Individual plants with blades broad, rounded / U. expansa
3 / Basally broadened, but upper portions divided deeply into many ribbon like segments; margins smooth, often undulate / U. fasciata
3 / Basally narrowing to a stipe up to 5 mm long, frond narrow, attenuate blades rarely divided, with strongly ruffled margins / U. taeniata
Key to the species of Monostroma
1 / Cells in surface view in packets, each packet separated from others by thin layers of cell wall / M. oxyspermum1 / Cells in surface view adjacent to one another, appearing parenchymatous / M. latissimum
Key to the species of Microdictyon
1 / Plants frequently covered with epiphytes, especially crustose coralline algae; nets coarse and conspicuous; individual cells frequently between 0.5 - 0.7 mm / M. setchellianum1 / Plants rarely carrying epiphytes, nets delicate, individual cells rarely more than 0.15 mm diam / M. japonicum
Key to the species of Bryopsis
1 / Erect axes branched from all sides (polystichously, radially), appearing somewhat tufted; branchlets successively shorter toward apex, or without pattern and unsymmetrical / B. hypnoides1 / Erect axes branched mostly from one or two (opposite) sides (distichously, pinnately), branchlets shorter toward apices, giving plumose, feathery appearance to axes / B. pennata
Key to the species of Dictyosphaeria
1 / Thalli hollow, with one layer of vesicle-like segments enclosing space, or expanded, ruptured; segments 0.5 - 5 mm wide / D. cavernosa1 / Thalli with small segments, to 2 mm wide, joined into a solid cushion / D. versluysii
Key to the species of Codium
1 / Plant without branches / 21 / Plant with branches / 6
2 / Plant irregularly shaped, flattened and adherent to substrate / 3
2 / Plant globular, spherical / 5
3 / Utricle apices with inwardly directed jagged processes / C. phasmaticum
3 / Utricles often pitted but not with distinctly inwardly directed processes / 4
4 / Plant firm, utricles of various shapes and sizes but mostly less than 1 mm. long, apical wall frequently pitted (alveolate) / C. arabicum
4 / Plant spongy, utricles mostly 1.5 - 3 mm long, 150 - 350 µm diam., apical wall not pitted / C. spongiosum
5 / Plant solid to hollow, but not thin, utricles to several mm long, often more than 1 mm diam (among the largest known in genus) / C. mamillosum
5 / Plant hollow, sack-like, thin, composed of utricles 250 - 280 µm long, mostly about 100 µm diam. / C. saccatum
6 / Plants with trailing, horizontal, divaricately dichotomous, terete branches secondarily attached to each other and to substrate, intertidal or shallow water / C. edule
6 / Plant with erect, dichotomous, terete branches tending to become unilateral as a result of unequal growth from the dichotomies; plant slightly flattened below, markedly flattened above; intertidal to shallow water / C. reediae
Key to the species of Valonia
1 / Septa between vesicles producing needle-like spines (trabeculae) / V. trabeculata1 / Septa between vesicles not producing trabeculae / V. aegagropila
Key to the species Cladophoropsis
1 / Filament diameters characteristically more than 400 µm , secondary attachment from ends of branches or by rhizoids developing laterally on segments / C. herpestica1 / Filament diameters mostly less than 300 µm , secondary attachment by specialized structures forming terminally or laterally from rhizoids / 2
2 / Filament diameters mostly 80 - 100 µm, secondary attachments infrequent / C. sundanensis
2 / Filament diameters mostly 150 - 300 µm, secondary attachments frequent / C. membranacea
Key to the species of Halimeda
1 / Plants prostrate, decumbent; holdfasts small, multiple, forming at base, along basal parts or as scattered attachments, sometimes inconspicuous / 21 / Plants erect or pendant, holdfast single, basal, sometimes massive or embedded in substrate, often not collected / 3
2 / Plants prostrate, branching mostly in one plane, branches spread out, not entangled; strictly deepwater / H. gracilis
2 / Plants decumbent or erect, branching in many planes; bushy, branches difficult to disentangle; more common in NWHI than in main island; intertidal to subtidal / H. opuntia
3 / Plants brittle, crumbly segments ; decalcified peripheral utricles free, bell-shaped; nodal regions with completely separate filaments / H. fragilis
3 / Plants with segments otherwise; nodal regions with filaments fused at the nodes, or having in same node both fused and separate filaments / 4
4 / Terminal segments elongate; cortex of 3 to 5 layers of utricles / H. incrassata
4 / Terminal segments not elongate, cortex never more than 4 layers / 5
5 / Plants to 10 cm tall, plants compact, segments close, di-trichotomously branched up to 25 mm wide, distal ones leather, not lobed / H. discoidea
5 / Plants up to 7 cm tall, plants spreading, segments loosely structured, flexible / 6
6 / Segments less than 5 mm wide, arranged in rounded rows, distal ones not different from ones below / H. velasquezii
6 / Segments more than 5 mm wide, not arranged in rounded rows / 7
7 / Nodal filaments fusing briefly, some filaments separate in the same node; branches spreading, segments irregular in shape / H. copiosa
7 / Nodal filaments fusing in 2’s , 3’s 4’s, decalcified segments showing polygonal or rounded cells in surface view / 8
8 / Plants with segments not heavily calcified, 12-125 mm wide; cortex 2 - 4 layers, primary utricles goblet or club-shaped in lateral view / H. tuna
8 / Plants with segments moderate calcified, tending to be brittle; cortex 2 - 3 layers, primary utricles elongate, occasionally their outer wall ornamented by a central spine / H. scabra
Key to the species of Acetabularia
1 / Ray cell more than 12, united laterally, forming a solid disk / A. parvula1 / Ray cells less than 10, united only at their bases / 2
2 / Ray cells laterally separated, attached only at their bases in a single plane / A. clavata
2 / Ray cells free, attached irregularly in many planes / A. exigua
Key to the species of Neomeris
1 / Calcification occurring in annular rows surrounding gametangia / N. annulata1 / Calcification not in rows but occurring around each globose gametangium / N. van-bosseae
Bornetella sphaericain the field, courtesy of Univ Tsukuba
Cladophora vagabunda Collector: Y. Song
Chaetomorpha antenninaCollector: P. Vroom, # 3-004
Enteromorpha prolifera
Ulva fasciataCaulerpa racemosa courtesy: Makoto Yoshizaki and Univ Tsukuba
Bryopsis pennata (Egerod 1952) Collector W McDowell, spring 2000l
Ventricaria ventricosa courtesy Univ Tsukuba, cultured plants
Avrainvillea amadelpha - upper portion only
Codium edule Collector: E. Goergen, Black Point, 2/7/99
Halimeda discoideaCollector: N. Murphy,Kualoa reef, 1/31/99