Sargassum, C. Agardh, 1820

Tu, Nguyen Van, 2023, Morpho-anatomical study of Sargassum (Fucales, Phaeophyceae) diversity reveals noteworthy collections and range extensions from southwestern Vietnam, Phytotaxa 600 (5), pp. 281-290 : 287-288

Key for Sargassum from southwestern Vietnam

1a. Axes with spines.................................................................................................................................................................................2

1b. Axes smooth .......................................................................................................................................................................................3

2a. Holdfasts lobed.................................................................................................................................................................. S. confusum

2b. Holdfasts conical, giving rise to stolon-like branches.................................................................................................... S. polycystum

3a. Axes compressed ................................................................................................................................................................................4

3b. Axes cylindrical..................................................................................................................................................................................6

4a. Leaves with entire margin ................................................................................................................................................... S. swartzii

4b Leaves with serrate margin.................................................................................................................................................................5

5a. Vesicles with terminal spines; petioles compressed or leaf-shaped; leaves thin ........................................................... S. oligocystum

5b. Vesicles on leaves; petioles compressed; leaves thick curved inside branches ..................................................................... S. feldmannii

6a. Leaves with entire or sparse spines, undulate ....................................................................................................................................7

6b. Leaves with sharply serrated margin..................................................................................................................................................8

7a. Basal leaves blunt at the apex; vesicles ovate ................................................................................................................... S. cinereum

7b. Basal leaves thick, larger and oval; vesicles oval or lanceolate ...................................................................................... S. siliquosum

8a. Vesicles spherical to obovate..............................................................................................................................................................9

8b. Vesicles leaf-shaped..........................................................................................................................................................................10

9a. Vesicles numerous; leaves lanceolate........................................................................................................................... S. microcystum

9b. Vesicles few; leaves obovate to spathulate ................................................................................................................................... S. ilicifolium

10a. Leaves serrated; midribs conspicuous up to ¾ of leaves................................................................................................. S. aquifolium

10b. Leaves spathulate to obovate; midribs inconspicuous..................................................................................................................... S. mcclurei