Chara, L.

Casanova, Michelle T. & Karol, Kenneth G., 2023, Charophytes of Australia’s Northern Territory - I. Tribe Chareae, Australian Systematic Botany 36 (1), pp. 38-79 : 47

Key to the species of Chara in the Northern Territory

1 Plants dioecious...............................................................................2 Plants monoecious...........................................................................7

2 Plant axis entirely ecorticate...........................................................3 Plant axis corticated, at least in part..............................................5

3 Axis diameter less than 700 µm, plants fine and tangled...... C. lucida Axis diameter greater than 700 µm, plants turgid and upright...... 4

4 Plants with small bract cells and stipulodes up to 850 µm long, branchlets incurved........................................................ C. porteri Plants with no visible bract cells and stipulodes, branchlets straight............................................................... C. protocharoides

5 Axial cortex cell number the same or fewer than the branchlets in the adjacent whorl, some branch apices contracted and filled with starch grains........................................................... C. submollusca Axial cortex cells 2× the number of the branchlets in the adjacent whorl...........................................................................................6

6 Bract cells on the branchlets abundant, 4–6, verticillate, stipulodes somewhat decumbent................................ C. lamprothamniformis Bract cells on the branchlets few, 2 or 3, somewhat unilateral, stipulodes spreading................................................... C. bancroftii

7 Stipulodes in one row, no gyrogonites present on oospores...........8 Stipulodes in two rows, gyrogonites present on oospores............14

8 Stipulodes evenly 2× the number of branchlets............................9 Stipulodes 1× the number of branchlets, sometimes with more, but never 2×...................................................................................10

9 Oogonia <300 µm long, oospores ~200 µm long, plants small, spine cells and bract cells very long (up to 1 mm) and abundant............. .................................................................................... C. arnhemensis Oogonia >400 µm long, oospores ~300 µm long, spine cells short...... .......................................................................................... C. schultae

10 Gametangia always arranged singly at the branchlet nodes, one oosporangium and one antheridium together...........................11 Gametangia arranged otherwise (sejoined, geminate or clustered).........................................................................................12

11 Stipulodes equal in number to the number of branchlets, branchlets long, bract cells few and plants somewhat calcified..................... .................................................................................. C. duriuscula Stipulodes one or two more than the number of branchlets, branchlets short and bract cells abundant, plants without calcification ................................................................................... C. benthamii

12 Gametangia sejoined and geminate in places, antheridia scarce, up to 700 µm wide....................................................... C. erythrogyna Gametangia conjoined, sometimes geminate and clustered, antheridia 200–500 µm wide.....................................................13

13 Branchlet tips a corona of equal-sized cells, oospores black............ ........................................................................................ C. karolii Branchlet tips a single cell subtended by bract cells, oospores brown.............................................................................. C. wightii

14 Branchlets largely without cortex, or cortex only on lowest cells.........................................................................................................15 Branchlets fully corticated except the final 1 or 2 segments........16

15 Branchlet cortex reduced to undeveloped cortical initials, gametangia on ecorticate nodes, axis isostichous..................... C. behriana Branchlet cortex present on a few lower branchlet internodes, gametangia only present where a cortex is present, axis aulacanthous...................................................................... C. aridicola

16 Basal branchlet cell cortex similar to all other corticated branchlet cells, plants smooth.................................................... C. globularis Basal branchlet cell cortex either absent or lacking pigmentation......17

17 Basal branchlet cell cortex absent, plants rough........... C. zeylanica Basal branchlet cell cortex lacking pigment, appearing different from other cortex, plants smooth.................................... C. setosa