Table of Characteristics for Angustifolium-Similar Species

Different authors subdivide genus Sparganium in different ways.  The following table lists characteristics of species similar to S. angustifolium.  The information is derived from the Flora of North America and Plants of the Western Boreal Forest & Aspen Parkland.  Note that each author includes species the other does not, and omits species the other includes.  The rarity abbreviations are C-common, UC-uncommon, END-endangered.  The rarity information is from the Checklist of the Vascular Plants of Saskatchewan.

Species

Flora of North America

Plants of the Western Boreal Forest

 Rarity
S. angustifolium Staminate heads 2 or more;
Rachis unbranched;
Tepals borne at or near base of fruit stipe;
Staminate heads contiguous, appearing as single elongate head;
Fruit beak 1.5--2 mm;
Leaves unkeeled		 At least two male flower heads;
Achene beaks straight or slightly curved;
Usually 2-3 female heads crowded and often not distinct;
Achene beaks 1.5-4 mm long;
Leaves usually 2-5 mm wide, rounded on back;
Fruiting heads 7-15 mm across

C
S. multipedunculatum   At least two male flower heads;
Achene beaks straight or slightly curved;
Usually 2-3 female heads crowded and often not distinct;
Achene beaks 1.5-4 mm long;
Leaves 5-10 mm wide, flat on back;
Fruiting heads 20-25 mm across

UC
S. emersum Staminate heads 2 or more;
Rachis unbranched;
Tepals borne at or near base of fruit stipe;
Staminate heads, or some of them, not contiguous;
Fruit beak 2--4.5 mm;
Leaves keeled toward base		    
S. chlorocarpum   At least two male flower heads;
Achene beaks straight or slightly curved;
Usually 4-7 distinct, widely separated female heads;
Achene beaks 2-5 mm long, about as long as body;
Stems and leaves stick up out of the water and overtop the flower cluster.

C
S. fluctuans Staminate heads 2 or more;
Rachis usually branched;
Tepals borne at middle of fruit stipe		 Achene beaks more than 1.5 mm long;
At least two male flower heads;
Several male and female heads;
Achene beaks flattened and strongly curved;
Floating stems;
Flat leaves all floating;

UC
S. minimum = S. natans Staminate heads 1(--2);
Inflorescence rachis unbranched;
Pistillate heads axillary and sessile or proximal head axillary and peduncled;
Fruit beak 0.5--1.5 mm		 Achene beaks less than 1.5 mm long;
1 male flower head;
Leaves 2-8 mm wide, translucent, usually dark green

C
S. hyperboreum Staminate heads 1(--2);
Inflorescence rachis unbranched;
Pistillate heads, at least one of them, supra-axillary and peduncled;
Fruit beak less than 0.5 mm, or absent		 Achene beaks less than 1.5 mm long;
1 male flower head;
Leaves 1-5 mm wide, opaque, often yellow;

END