Tanacetum densum var. amani forms evergreen, textured mats of soft, feathery, silver foliage and bright yellow button-like flowers.
Thermopsis chinensis 'Sophia' is a lupin relative with canary yellow flowers blooming at the same time as tulips and daffodils.
Tigridia pavonia 'Aurea' is an Iris relative with large, three-petaled yellow flowers with red central spots.
Tigridia pavonia 'Canariensis' is an Iris relative with large, three-petaled pale yellow flowers with red central spots.
Titanopsis calcarea or concrete leaf has grey-green spoon-shaped leaves covered in rough tubercles that look like concrete.
Woodland foxglove or Titanotrichum oldhami has spikes of golden yellow bells with vivid, cinnamon-red throats.
Tricyrtis flava is a rare toadlily with yellow flowers for late summer colour in the shade garden.
Tricyrtis ‘Golden Festival’ forms compact plants with attractive yellow orchid-like flowers with bronze dots.
Tricyrtis ‘Moonlight Treasure' has mottled foliage and large, soft yellow flowers.
Pale yellow flowers with bronze dots look like intricate orchids in the shade garden.
Triteleia ixioides 'Starlight' produces clusters of two inch, creamy yellow, star-like flowers with purple-brown mid veins.
Trollius 'Alabaster' has semi double, spherical, soft butter yellow flowers. Globe flowers are very hardy and easy to grow.
Trollius 'Lemon Queen' has spherical, golden yellow flowers. Globe flowers are very hardy and easy to grow.
Tropaeolum brachyceras is a climbing nasturtium with small leaves and thin tubular bright yellow flowers.
Tulipa 'Easter Surprise' has bold, lemon-yellow flowers with red, orange or peach highlights sitting just above the blue-green foliage.
Tulipa heweri is a new species of botanical tulip discovered in 2008 with yellow or ochre flowers and orange on the outer petals.
Tulipa kaufmanniana 'Waterlily' has bell-shaped, upward facing, pale yellow flowers whose petals flare, reflexing outwards.
Tulipa kolpakowskiana is a botanical tulip with yellow flowers streaked in carmine red atop narrow, undulating leaves.
Tulipa linifolia (Batalinii Group) 'Apricot Jewel' begins clear yellow orange acquiring peach tones and red highlights above narrow, twisted foliage.
Tulipa linifolia (Batalinii Group) 'Honky Tonk' is a beautiful tulip in shades of pale lemon yellow sometimes flushed with pink above narrow, twisted foliage.
Tulipa marjolettii is a tall tulip with creamy yellow flowers with a pink flush.
Tulipa sylvestris, the woodland tulip, is a tall botanical tulip with arching or nodding golden yellow buds with green mid ribs opening upwards to starry blooms.