plocamium at a glance · “algae revealed: plocamium at a glance”, r n baldock, state herbarium,...

“Algae Revealed: Plocamium at a glance”, R N Baldock, State Herbarium, S Australia, March 2013

SOUTHERN AUSTRALIAN SPECIES OF PLOCAMIUM AT A GLANCE (microscope views are often stained blue, preserved specimens are colourless; the coin scale is 24mm or almost 1” wide)

In this genus, ultimate branches (ramuli) are flat, paper thin, occasionally cylindrical but flattened in pressed specimens, pointed, arranged in sets of 2’s, or 3’s, 4’s and 5’s alternating along opposite sides of major branches (axes), repeated also on side branches. 1.0: SHORT SIDE BRANCHES (RAMULI) ALTERNATE ALONG MAIN BRANCHES (AXES) IN PAIRS

1.1 MAJOR BRANCHES (AXES) NARROW, ! 2 mm WIDE, MATURE FEMALE STRUCTURES (CYSTOCARPS) STALKLESS

A1

A2 B1

B2

C2

D1

side branches in alternating pairs (A1 A2 / B1 B2... etc.)!

C1

D2

stalkless ball-shaped mature female structures (cystocarps. cys)

major branches (axes) ! 1 mm wide, ultimate branches (ramuli) not serrated (but can be divided into prong-like branches) " Plocamium angustum

major branches (axes) 1-2 mm wide, lower of the ramuli pairs is serrated " Plocamium costatum

alternating branch pairs (A1, A2, - B1, B2,)

lower member serrated on lower edge

A1 A2

B2 B1

cys


major branches (axes) usually < 3 mm wide; plants delicate, but often large (to 500 mm tall); ramuli pairs variable, the upper one continues growing, repeating the alternating paired branching pattern found in the axes, the lower one is occasionally serrate, or forked many times forming tree like tufts " Plocamium mertensii

1.2 MAJOR BRANCHES (AXES) > 2 mm WIDE, MATURE FEMALE STRUCTURES (CYSTOCARPS) ON STALKS


continued next page

major branches (axes) ! 4 mm wide; upper ramulus of a pair is stubby, and has finger-like branching, lower one is unbranched and not serrate

" Plocamium patagiatum

A1 A2

B2

B2

short side branches (ramuli) alternate in pairs along the axis (two pairsA1, A2 and B1, B2 are shown)

denuded (bottom) and normal axes (above)

paired ramuli (A1, A2 etc.)

A2

A1

B1

B2 C1

C2

alternative branching pattern in which ramuli are densely forked into tree-like tufts

branching pattern where the upper ramulus of a pair continues growing

cystocarps stalked, in ramuli forks (axils)


clusters of large sporangial structures (stichidia) in forks (axils) of ramuli


(CONTINUED)

major branches (axes) ! 2.5 mm wide, with a mid-rib in older parts; plants robust, but small (to 240 mm tall); lower member of the alternating pairs of ramuli is serrate and undivided; sporangial structures are large (250 µm wide)

" Plocamium dilatatum

alternating pairs of ramuli (A1 A2 ! B1 B2 etc.). The lower member of the pair is serrate. Axes are developing a central mid-rib

A1

A2 B1

B2

C1 C2

stalked cystocarps


cystocarps smooth

2.0 Ramuli in 3-5’s continued next page

2.0: SHORT SIDE BRANCHES (RAMULI) IN SERIES OF 3, 4 OR 5’s (RARELY PAIRED)

ALTERNATING ALONG MAJOR BRANCHES (AXES)

axes ! 2 mm wide, thickened below, ramuli in 3’s; stichidia clustered at bases of ramuli forks; cystocarps stalkless and warty

" Plocamium preissianum

B1

B2

C1

C2

A1

A3

C3

A2

B3

clusters of young stichidia at the base of ramuli forks

ramuli in 3’s, (A1, A2, A3, etc) alternating along axes

warty cystocarps

A1

A2

A4

A5

A3

B1

B2

B3

B4

B5

ramuli in 5’s, uppermost ramuli in a series are branched, lowest are unbranched, and smooth

stichidia along inner edges of ramuli forks

axes ! 1mm wide; ramuli in 3’s, 4’s or 5’s, the several upper ramuli in a series are branched, the lowest is unbranched, smooth; cystocarps smooth; stichidia found along edges of forks between ramuli — Plocamium

cartilagineum


forked sporangial structures (stichidia) on the edges of ramuli

A1

A2

A3

A4

B1

B2

B3

B4

C1

C2

C3

C4

ad br

ad br

ad br

ad br

often growing on other algae (epiphytic). Axes ! 0.5 mm wide, often floppy, ends of branches often re-curved or hooked; short side branches (ramuli) in 3’s, 4’s or 5’s, alternating along axes, the several upper ramuli in a series are branched, the lowest unbranched but the pattern is quickly obscured by additional (adventitious) ramuli; rare sporangial structures (stichidia) on edges of ramuli are forked (sexual stages are unknown) — Plocamium leptophyllum

branch ends commonly hooked

alternating series of ramuli in 4’s, (A1...A4 " B1... B4!"#$%&'!()*"+#!,-./(/+!/01,-0$2"3'!4-##",0!)1+$/,"3!15!-336#6)0-(!,-./(6!7!"#$%&!


Callophyllis rangiferina

Austrophyllis alcicornis

branching pattern of Callophyllis rangiferina branching pattern of Callophyllis lambertii

Calliblepharis planicaulis: two magnifications

PLOCAMIUM LOOK-ALIKES

Callophyllis and Austrophyllis these flat-branched species may superficially resemble Plocamium but short side branches are

• irregularly forked • do not occur

in series of 2’s, 3’s, 4’s, or 5’s and,

• reproductive organs form swellings embedded in the flat branches

Calliblepharis planicaulis this has fine alternating side branches, some with hooked ends similar to Plocamium leptophyllum, but reproductive organs form swellings embedded in the branches, and the surface has large cells ringed by small cells (rosettes)

PLOCAMIUM LOOK-ALIKES contnued next page


PLOCAMIUM LOOK-ALIKES (CONTINUED)

Ptilonia spp These have alternating flat side branches but short side branches are • irregularly forked, or • do not occur in series of 2’s, 3’s, 4’s, or 5’s and, • reproductive organs form apical swellings • there is a prominent central filament running through the flattened branches

Ptilonia australasicum, branching pattern and terminal cystocarps

Ptilonia subulifera, branching pattern , terminal cystocarps and cross section

plocamium at a glance · “algae revealed: plocamium at a glance”, r n baldock, state herbarium,...

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