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 2,401–2,450 of 3,901.

• 
  Onosmodium bejariense DC. ex A. DC. Native ONBE

  soft-hair marbleseed · Boraginaceae 6 counties
• 
  Onosmodium bejariense DC. ex A. DC. var. hispidissimum (Mack.) B.L. Turner Native ONBEH

  softhair marbleseed · Boraginaceae 6 counties
• 
  Onosmodium virginianum (L.) A. DC. Native ONVI2

  wild Job's tears · Boraginaceae 2 counties
• 
  Ophioglossum engelmannii Prantl Native OPEN

  limestone adderstongue · Ophioglossaceae 1 county
• 
  Ophioglossum pusillum Raf. Native OPPU3

  northern adderstongue · Ophioglossaceae 33 counties
• 
  Ophioglossum vulgatum L. Native OPVU

  southern adderstongue · Ophioglossaceae 8 counties
• 
  Opuntia humifusa (Raf.) Raf. Native OPHU

  devil's-tongue · Cactaceae 14 counties
• 
  Origanum majorana L. Introduced ORMA

  sweet marjoram · Lamiaceae 2 counties
• 
  Origanum vulgare L. Introduced ORVU

  oregano · Lamiaceae 13 counties
• 
  Ornithogalum nutans L. Introduced ORNU

  drooping star of Bethlehem · Liliaceae 10 counties
• 
  Ornithogalum umbellatum L. Introduced ORUM

  star of Bethlehem · Liliaceae 40 counties
• 
  Ornithopus perpusillus L. Introduced ORPE80

  little white bird's-foot · Fabaceae 2 counties
• 
  Orobanche minor Sm. Introduced ORMI

  hellroot · Orobanchaceae 3 counties
• 
  Orobanche uniflora L. Native ORUN

  oneflowered broomrape · Orobanchaceae 55 counties
• 
  Orontium aquaticum L. Native ORAQ

  goldenclub · Araceae 37 counties
• 
  Orthilia secunda (L.) House Native ORSE

  sidebells wintergreen · Pyrolaceae 33 counties
• 
  Oryzopsis asperifolia Michx. Native ORAS

  roughleaf ricegrass · Poaceae 24 counties
• 
  Osmorhiza claytonii (Michx.) C.B. Clarke Native OSCL

  Clayton's sweetroot · Apiaceae 53 counties
• 
  Osmorhiza longistylis (Torr.) DC. Native OSLO

  longstyle sweetroot · Apiaceae 60 counties
• 
  Osmunda cinnamomea L. Native OSCI

  cinnamon fern · Osmundaceae 66 counties
• 
  Osmunda claytoniana L. Native OSCL2

  interrupted fern · Osmundaceae 67 counties
• 
  Osmunda regalis L. Native OSRE

  royal fern · Osmundaceae 62 counties
• 
  Osmunda regalis L. var. spectabilis (Willd.) A. Gray Native OSRES

  royal fern · Osmundaceae 62 counties
• 
  Ostrya virginiana (Mill.) K. Koch Native OSVI

  hophornbeam · Betulaceae 61 counties
• 
  Oxalis corniculata L. Native OXCO

  creeping woodsorrel · Oxalidaceae 18 counties
• 
  Oxalis dillenii Jacq. Native OXDI2

  slender yellow woodsorrel · Oxalidaceae 56 counties
• 
  Oxalis grandis Small Native OXGR

  great yellow woodsorrel · Oxalidaceae 21 counties
• 
  Oxalis montana Raf. Native OXMO

  mountain woodsorrel · Oxalidaceae 41 counties
• 
  Oxalis stricta L. Native OXST

  common yellow oxalis · Oxalidaceae 67 counties
• 
  Oxalis violacea L. Native OXVI

  violet woodsorrel · Oxalidaceae 46 counties
• 
  Oxydendrum arboreum (L.) DC. Native OXAR

  sourwood · Ericaceae 6 counties
• 
  Oxypolis rigidior (L.) Raf. Native OXRI

  stiff cowbane · Apiaceae 17 counties
• 
  Pachysandra procumbens Michx. Native PAPR7

  Allegheny-spurge · Buxaceae 3 counties
• 
  Pachysandra terminalis Siebold & Zucc. Introduced PATE11

  Japanese pachysandra · Buxaceae 6 counties
• 
  Packera anonyma (Alph. Wood) W.A. Weber & Á. Löve Native PAAN6

  Small's ragwort · Asteraceae 10 counties
• 
  Packera antennariifolia (Britton) W.A. Weber & Á. Löve Native PAAN7

  shale barren ragwort · Asteraceae 3 counties
• 
  Packera aurea (L.) Á. Löve & D. Löve Native PAAU3

  golden ragwort · Asteraceae 67 counties
• 
  Packera obovata (Muhl. ex Willd.) W.A. Weber & Á. Löve Native PAOB6

  roundleaf ragwort · Asteraceae 47 counties
• 
  Packera paupercula (Michx.) Á. Löve & D. Löve Native PAPA20

  balsam groundsel · Asteraceae 24 counties
• 
  Packera plattensis (Nutt.) W.A. Weber & Á. Löve Native PAPL12

  prairie groundsel · Asteraceae 1 county
• 
  Paeonia lactiflora Pall. Introduced PALA27

  Chinese peony · Paeoniaceae 5 counties
• 
  Panax quinquefolius L. Native PAQU

  American ginseng · Araliaceae 53 counties
• 
  Panax trifolius L. Native PATR2

  dwarf ginseng · Araliaceae 59 counties
• 
  Panicum amarum Elliott Native PAAM2

  bitter panicgrass · Poaceae 2 counties
• 
  Panicum amarum Elliott var. amarulum (Hitchc. & Chase) P.G. Palmer Native PAAMA2

  coastal panicgrass · Poaceae 1 county
• 
  Panicum amarum Elliott var. amarum Native PAAMA3

  bitter panicgrass · Poaceae 2 counties
• 
  Panicum anceps Michx. Native PAAN

  beaked panicgrass · Poaceae 15 counties
• 
  Panicum bisulcatum Thunb. Introduced PABI80

  Japanese panicgrass · Poaceae 1 county
• 
  Panicum capillare L. Native PACA6

  witchgrass · Poaceae 63 counties
• 
  Panicum dichotomiflorum Michx. Native PADI

  fall panicgrass · Poaceae 60 counties