Pennsylvania

• Adams 42001
  1,101 taxa Open ↗
• Allegheny 42003
  1,943 taxa Open ↗
• Armstrong 42005
  1,126 taxa Open ↗
• Beaver 42007
  1,402 taxa Open ↗
• Bedford 42009
  1,989 taxa Open ↗
• Berks 42011
  2,115 taxa Open ↗
• Blair 42013
  1,613 taxa Open ↗
• Bradford 42015
  1,111 taxa Open ↗
• Bucks 42017
  2,298 taxa Open ↗
• Butler 42019
  1,422 taxa Open ↗

Showing 251–300 of 3,901.

• 
  Arctium tomentosum Mill. Introduced ARTO

  woolly burdock · Asteraceae 5 counties
• 
  Arctium vulgare (Hill) Evans Introduced ARVU2

  woodland burdock · Asteraceae 15 counties
• 
  Arctostaphylos uva-ursi (L.) Spreng. Native ARUV

  kinnikinnick · Ericaceae 4 counties
• 
  Arenaria serpyllifolia L. Introduced ARSE2

  thymeleaf sandwort · Caryophyllaceae 58 counties
• 
  Arethusa bulbosa L. Native ARBU

  dragon's mouth · Orchidaceae 11 counties
• 
  Argemone mexicana L. Native ARME4

  Mexican pricklypoppy · Papaveraceae 5 counties
• 
  Argentina anserina (L.) Rydb. Native ARAN7

  silverweed cinquefoil · Rosaceae 2 counties
• 
  Arisaema dracontium (L.) Schott Native ARDR3

  green dragon · Araceae 45 counties
• 
  Arisaema triphyllum (L.) Schott Native ARTR

  Jack in the pulpit · Araceae 67 counties
• 
  Arisaema triphyllum (L.) Schott ssp. pusillum (Peck) Huttleston Native ARTRP

  Jack in the pulpit · Araceae 39 counties
• 
  Arisaema triphyllum (L.) Schott ssp. stewardsonii (Britton) Huttleston Native ARTRS

  Jack in the pulpit · Araceae 51 counties
• 
  Arisaema triphyllum (L.) Schott ssp. triphyllum Native ARTRT3

  Jack in the pulpit · Araceae 67 counties
• 
  Aristida dichotoma Michx. Native ARDI4

  churchmouse threeawn · Poaceae 48 counties
• 
  Aristida dichotoma Michx. var. curtissii A. Gray Native ARDIC

  Curtis' threeawn · Poaceae 2 counties
• 
  Aristida dichotoma Michx. var. dichotoma Native ARDID

  churchmouse threeawn · Poaceae 47 counties
• 
  Aristida longespica Poir. Native ARLO16

  slimspike threeawn · Poaceae 12 counties
• 
  Aristida longespica Poir. var. geniculata (Raf.) Fernald Native ARLOG6

  slimspike threeawn · Poaceae 3 counties
• 
  Aristida longespica Poir. var. longespica Native ARLOL3

  slimspike threeawn · Poaceae 12 counties
• 
  Aristida oligantha Michx. Native AROL

  prairie threeawn · Poaceae 18 counties
• 
  Aristida purpurascens Poir. Native ARPU8

  arrowfeather threeawn · Poaceae 8 counties
• 
  Aristida purpurascens Poir. var. purpurascens Native ARPUP4

  arrowfeather threeawn · Poaceae 7 counties
• 
  Aristolochia clematitis L. Introduced ARCL

  birthwort · Aristolochiaceae 3 counties
• 
  Aristolochia macrophylla Lam. Native ARMA7

  pipevine · Aristolochiaceae 10 counties
• 
  Aristolochia serpentaria L. Native ARSE3

  Virginia snakeroot · Aristolochiaceae 31 counties
• 
  Armoracia rusticana G. Gaertn., B. Mey. & Scherb. Introduced ARRU4

  horseradish · Brassicaceae 34 counties
• 
  Arnica acaulis (Walter) Britton, Sterns & Poggenb. Native ARAC3

  common leopardbane · Asteraceae 2 counties
• 
  Arnoglossum atriplicifolium (L.) H. Rob. Native ARAT

  pale Indian plantain · Asteraceae 49 counties
• 
  Arnoglossum reniforme (Hook.) H. Rob. Native ARRE6

  great Indian plantain · Asteraceae 9 counties
• 
  Arnoseris minima (L.) Schweigg. & Körte Introduced ARMI3

  lamb succory · Asteraceae 1 county
• 
  Aronia arbutifolia (L.) Pers. Native ARAR7

  red chokeberry · Rosaceae 51 counties
• 
  Aronia melanocarpa (Michx.) Elliott Native ARME6

  black chokeberry · Rosaceae 57 counties
• ⚘
  Aronia ×prunifolia (Marshall) Rehder, (pro sp.) [arbutifolia × melanocarpa] Native ARPR2

  purple chokeberry · Rosaceae 46 counties
• 
  Arrhenatherum elatius (L.) P. Beauv. ex J. Presl & C. Presl Introduced AREL3

  tall oatgrass · Poaceae 55 counties
• 
  Arrhenatherum elatius (L.) P. Beauv. ex J. Presl & C. Presl var. elatius Introduced ARELE

  tall oatgrass · Poaceae 55 counties
• 
  Artemisia absinthium L. Introduced ARAB3

  absinthium · Asteraceae 7 counties
• 
  Artemisia annua L. Introduced ARAN3

  sweet sagewort · Asteraceae 13 counties
• 
  Artemisia biennis Willd. Both ARBI2

  biennial wormwood · Asteraceae 6 counties
• 
  Artemisia biennis Willd. var. biennis Introduced ARBIB

  biennial wormwood · Asteraceae 6 counties
• 
  Artemisia campestris L. Native ARCA12

  field sagewort · Asteraceae 3 counties
• 
  Artemisia campestris L. ssp. caudata (Michx.) H.M. Hall & Clem. Native ARCAC

  field sagewort · Asteraceae 3 counties
• 
  Artemisia frigida Willd. Native ARFR4

  prairie sagewort · Asteraceae 2 counties
• 
  Artemisia ludoviciana Nutt. Both ARLU

  white sagebrush · Asteraceae 12 counties
• 
  Artemisia ludoviciana Nutt. ssp. ludoviciana Native ARLUL2

  white sagebrush · Asteraceae 12 counties
• 
  Artemisia pontica L. Introduced ARPO4

  Roman wormwood · Asteraceae 7 counties
• 
  Artemisia stelleriana Besser Introduced ARST6

  oldwoman · Asteraceae 3 counties
• 
  Artemisia vulgaris L. Introduced ARVU

  common wormwood · Asteraceae 1 county
• 
  Arthraxon hispidus (Thunb.) Makino Introduced ARHI3

  small carpetgrass · Poaceae 9 counties
• 
  Aruncus dioicus (Walter) Fernald Both ARDI8

  bride's feathers · Rosaceae 18 counties
• 
  Aruncus dioicus (Walter) Fernald var. dioicus Native ARDID2

  bride's feathers · Rosaceae 18 counties
• 
  Arundinaria tecta (Walter) Muhl. Both ARTE4

  switchcane · Poaceae 1 county