Identification of Tropical Spiderwort Identification of Tropical Spiderwort (AKA Benghal Dayflower)(AKA Benghal Dayflower)

Theodore M. Webster Theodore M. Webster

USDA-ARS, TiftonUSDA-ARS, Tifton

Twebster@tifton.usda.govTwebster@tifton.usda.gov

Eric Prostko, UGAEric Prostko, UGA

Coteledonary stalk – links seed to Coteledonary stalk – links seed to meristem (common in Commelinaceae)meristem (common in Commelinaceae)

Photo by Stanley Culpepper, UGAPhoto by Stanley Culpepper, UGA

Relative to other dayflowers, tropical spiderwort has

broad, short leaves

Leaf Length: Leaf Width ~ 1.5Leaf Length: Leaf Width ~ 1.5

(Less than 3:1)(Less than 3:1)Alan York, NCSUAlan York, NCSU

Of the 170 Of the 170 CommelinaCommelina spp., it is one of a few spp., it is one of a few that is vegetatively distinct (Faden 1992)that is vegetatively distinct (Faden 1992)

TROPICAL SPIDERWORTTROPICAL SPIDERWORTTip more bluntedTip more bluntedL:W Ratio <3:1L:W Ratio <3:1

SPREADING DAYFLOWERSPREADING DAYFLOWERTip sharperTip sharper

L:W Ratio L:W Ratio >>4:14:1

Mike Burton, NCSUMike Burton, NCSU

4.34.3

1.01.01.51.51.01.0

MARSH DAYFLOWERMARSH DAYFLOWERL:W Ratio ~ 6:1L:W Ratio ~ 6:1

Red Hairs at the Red Hairs at the apex of the apex of the

membranous sheathmembranous sheath

Herb Pilcher, USDA-ARSHerb Pilcher, USDA-ARS

Dayflower/Spiderwort Flowers Dayflower/Spiderwort Flowers (Commelina spp.)(Commelina spp.)

Asiatic DayflowerAsiatic Dayflower

Spreading DayflowerSpreading Dayflower

Tropical spiderwortTropical spiderwort

From SWSS Weed ID GuideFrom SWSS Weed ID Guide

From SWSS Weed ID GuideFrom SWSS Weed ID Guide

This slide is a bit deceiving,This slide is a bit deceiving,as tropical spiderwort flowersas tropical spiderwort flowersare much smaller than its twoare much smaller than its two

dayflower relativesdayflower relatives

Herb Pilcher, USDA-ARSHerb Pilcher, USDA-ARS

3 blue petals3 blue petals

Upper 2 petals blueUpper 2 petals blueLower petal whiteLower petal white

Fused Conical Spathe: Important Identifying Characteristic!Fused Conical Spathe: Important Identifying Characteristic!

Mike Burton, NCSUMike Burton, NCSU

Top View: Spreading DayflowerTop View: Spreading Dayflower

Side View:Side View:Spreading DayflowerSpreading Dayflower

FusedFusedNot FusedNot Fused

Asiatic DayflowerAsiatic Dayflower

Tropical SpiderwortTropical Spiderwort

Of the nearly 250,000 species of flowering plants…Of the nearly 250,000 species of flowering plants…

… … 36 have underground flowers36 have underground flowers

Herb Pilcher, USDA-ARSHerb Pilcher, USDA-ARS

Only dayflower speciesOnly dayflower speciesin the U.S. to havein the U.S. to have

underground flowersunderground flowers

Underground flowersUnderground flowers

2002 Arlene Mendoza2002 Arlene Mendoza

North Carolina State UniversityNorth Carolina State University

Key Characteristics for Tropical Key Characteristics for Tropical Spiderwort IdentificationSpiderwort Identification

• Leaf Length to Leaf Width Ratio <3:1; other Leaf Length to Leaf Width Ratio <3:1; other dayflowers are 4:1 or greaterdayflowers are 4:1 or greater

• Underground flowers – unique among Underground flowers – unique among dayflowers in the USdayflowers in the US

• Aerial flowers are much smaller than other Aerial flowers are much smaller than other dayflowers; 2 upper petals blue, lower one dayflowers; 2 upper petals blue, lower one whitewhite

• Red (or white) hairs at the apex of the sheath Red (or white) hairs at the apex of the sheath that surrounds the stemthat surrounds the stem

WWW.GAWeed.comWWW.GAWeed.com

Twebster@tifton.usda.govTwebster@tifton.usda.gov