Scientific names: K
- Kagawara Christie Low
- Kalanchoe arborescens
- Kalanchoe blossfeldiana
- Kalanchoe bouvetii
- Kalanchoe campanulata
- Kalanchoe daigremontiana
- Kalanchoe eriophylla
- Kalanchoe fedtschenkoi
- Kalanchoe jongmansii
- Kalanchoe laetivirens
- Kalanchoe lateritia
- Kalanchoe latisepala
- Kalanchoe manginii
- Kalanchoe marnieriana
- Kalanchoe millotii
- Kalanchoe nyikae
- Kalanchoe pumila
- Kalanchoe tomentosa
- Kali turgida
- Kalimeris incisa
- Kalmia angustifolia 'Rubra'
- Kalmia latifolia
- Kalmia latifolia 'Bandeau'
- Kalmia latifolia 'Carol'
- Kalmia latifolia 'Cheerful'
- Kalmia latifolia 'Comet'
- Kalmia latifolia 'Kaleidoscope'
- Kalmia latifolia 'Marienkäfer'
- Kalmia latifolia 'Mitternacht'
- Kalmia latifolia 'Nani'
- Kalmia latifolia 'Pinkobello'
- Kalmia latifolia 'Rosenquarz'
- Kalmia polifolia
- Kalopanax septemlobus
- Kennedia rubicunda
- Kerria japonica
- Kerria japonica 'Pleniflora'
- Kigelia africana
- Kigelia pinnata
- Kirengeshoma palmata
- Kitaibelia vitifolia
- Kleinia fulgens
- Knautia Melton Pastels
- Knautia drymeia
- Knautia macedonica
- Knautia macedonica 'Mars Midget'
- Knautia sarajevensis
- Kniphofia Green Magic
- Kniphofia caulescens
- Kniphofia ensifolia
- Kniphofia linearifolia
- Kniphofia sarmentosa
- Kniphofia triangularis
- Kniphofia uvaria
- Kniphofia uvaria 'Elveria'
- Kniphofia uvaria 'Flamenco'
- Kniphofia uvaria 'Nobilis'
- Kochia scoparia
- Koeleria glauca
- Koelreuteria paniculata
- Koelreuteria paniculata var. apiculata
- Kohleria lindeniana
- Kohleria ocellata
- Kolkwitzia amabilis
- Kolkwitzia amabilis 'Pink Cloud'
- Kopsia fruticosa
- Korolkowia sewerzowii