Phleum arenarium
Sand Cat's-tail
Phleum bertolonii
Smaller Cat's-tail
Phleum pratense
Timothy
Phoenix dactylifera
Date Palm
Phormium cookianum
Lesser New Zealand Flax
Phragmites australis
Common Reed
Pistia stratiotes
Water Cabbage
Platanthera bifolia
Lesser Butterfly-orchid
Platanthera chlorantha
Greater Butterfly-orchid
Platanthera x hybrida
Pleione formosana
Pleione
Poa annua
Annual Meadow-grass
Poa compressa
Flattened Meadow-grass
Poa humilis
Spreading Meadow-grass
Poa trivialis
Rough Meadow-grass
Polygonatum multiflorum
Solomon's-seal
Polygonatum odoratum
Angular Solomon's-seal
Polygonatum verticillatum
Whorled Solomon's-seal
Polygonatum x hybridum
Garden Solomon's-seal
Polypogon viridis
Water Bent
Pontederia crassipes
Water Hyacinth
Potamogeton coloratus
Fen Pondweed
Potamogeton crispus
Curled Pondweed
Potamogeton lucens
Shining Pondweed
Potamogeton natans
Broad-leaved Pondweed
Potamogeton polygonifolius
Bog Pondweed
Pseudorchis albida
Small-white Orchid
Ravenala madagascariensis
East-West Palm
Rhynchospora alba
White Beak-sedge
Rhynchospora fusca
Brown Beak-sedge
Romulea columnae
Sand Crocus
Ruppia maritima
Beaked Tasselweed
Ruscus aculeatus
Butcher's-broom
Sagittaria sagittifolia
Arrowhead
Schedonorus giganteus
Giant Fescue
Scheuchzeria palustris
Rannoch-rush
Schismatoglottis calyptrata
Dukaruk
Schizostylis coccinea
Kaffir Lily
Schoenoplectus lacustris
Common Club-rush
Schoenoplectus tabernaemontani
Grey Club-rush
Schoenus nigricans
Black Bog-rush
Scilla autumnalis
Autumn Squill
Scilla bifolia
Alpine Squill
Scilla forbesii
Glory-of-the-snow
Scilla liliohyacinthus
Pyrenean Squill
Scilla luciliae
Boissier's Glory-of-the-snow
Scilla peruviana
Portuguese Squill
Scilla siberica
Siberian Squill
Scilla verna
Spring Squill
Scindapsus pictus
Satin Pothos
Scirpoides holoschoenus
Round-headed Club-rush
Scirpus sylvaticus
Wood Club-rush
Secale cereale
Rye
Setaria palmifolia
Palm Grass
Setaria verticillata
Hooked Bristlegrass
Setaria viridis
Green Bristle-grass
Simethis mattiazzii
Kerry Lily
Sisyrinchium bermudiana
Blue-eyed-grass
Sisyrinchium montanum
American Blue-eyed-grass
Sparganium angustifolium
Floating Bur-reed
Sparganium erectum
Branched Bur-reed
Sparganium natans
Least Bur-reed
Spartina anglica
Common Cord-grass
Spathiphyllum blandum
Pleasant Peace Lily
Spathoglottis plicata
Philippine Ground Orchid
Spiranthes romanzoffiana
Irish Lady's-tresses
Spiranthes spiralis
Autumn Lady's-tresses
Spirodela polyrhiza
Greater Duckweed
Sternbergia lutea
Winter Daffodil
Stromanthe thalia