- Group 1Lycophytes, Monilophytes
- Group 2Gymnosperms
- Group 3Monocots
- Group 4Woody angiosperms with opposite or whorled leaves
- Group 5Woody angiosperms with alternate leaves
- Group 6Herbaceous angiosperms with inferior ovaries
- Group 7Herbaceous angiosperms with superior ovaries and zygomorphic flowers
- Group 8Herbaceous angiosperms with superior ovaries, actinomorphic flowers, and 2 or more distinct carpels
- Group 9Herbaceous angiosperms with superior ovaries, actinomorphic flowers, connate petals, and a solitary carpel or 2 or more connate carpels
- Group 10Herbaceous angiosperms with superior ovaries, actinomorphic flowers, distinct petals or the petals lacking, and 2 or more connate carpels
Trichostema is often defined as excluding Isanthus based on floral differences. However, phylogenetic research showed that Isanthus is properly part of the genus Trichostema (Huang 2002).
1b. Calyx zygomorphic; stamens conspicuously arched [Fig. 707], 12–20 mm long; 2 principal veins of leaf blade not reconnecting to midvein or the lateral veins absent altogether
Show photos of: Each photo represents one species in this genus.