Key 5:

SECTION 5:
Sporangium predominantly obovoid, obovate, or obpyriform (the part of the sporangium distal to the substrate is broadest).

Section 5


  1. Sporangium born on a stalk..............................................................2

Sporangium sessile on substrate.......................................................8

  1. Stalk robust....................................................................................3

Stalk thin.......................................................................................4

  1. Sporangium multi-pored....................................R. spinosum Willoughby

Sporangium single-pored........................R. spinosum Karling (homonym)

  1. Stalk isodiametic, short or long.........................................................5

Stalk clavate...............................................................R. pedicellatum

  1. Spores discharged through 1-4 pores..................................................6

Spores released as entire sporangial wall deliquesces............R. piriformis

  1. Apical pore opening broad, rim reflexed..............................R. echinatum

Apical pore(s) not broad, rim not reflexed...........................................7

  1. Rhizoids branched...............................................................R. fulgens

Rhizoids unbranched.....................................................R. obpyriformis

  1. Zoospore discharge through a pore....................................................9

Upper half of sporangium deliquesces to liberated..............................12

  1. Discharge pore apical.....................................................................10

Discharge pore lateral....................................................R. parasiticum

  1. Sporangium conchiforme in shape...................................R. conchiforme

Sporangium clavate, pear-shaped, or oval..........................................11

  1. Sporangium clavate, rhizoids robust and branched.................R. clavatum

Sporangium pear-shaped or oval, rhizoid very slender...............R. ovatum

  1. Rhizoid unbranched............................................................R. clinopus

Rhizoid branched, coarse, tapering.....................................R. pelagicum

 



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