buttonweed

Short definition from Wiktionary

Noun

1. 1
   Any of numerous species of plants with button-like flowers, especially: Any of several plants of the genera Diodia and Hexasepalum (syn. Diodella), of the madder family.
2. 2
   Any of numerous species of plants with button-like flowers, especially: False buttonweed (Spermacoce spp.).
3. 3
   Any of numerous species of plants with button-like flowers, especially: Velvetleaf, Indian mallow (Abutilon theophrasti).
4. 4
   Any of numerous species of plants with button-like flowers, especially: Certain knapweeds (Centaurea spp.).
5. 5
   Any of numerous species of plants with button-like flowers, especially: Clustered bluet (Oldenlandia uniflora).
6. 6
   Any of numerous species of plants with button-like flowers, especially: Dwarf mallow, common mallow (Malva neglecta).
7. 7
   Any of numerous species of plants with button-like flowers, especially: Water buttons (Cotula spp.).