In frog, the vertebra with an anterior convex surface (i.e., double convexties) is
atlas
urostyle
8th vertebra
9th vertebra
Plants growing on sand and gravel are called
eremophytes
psammophytes
psilophytes
oxylophytes
B.
psammophytes
Psammophytes grow in sand and gravel, eremophytes grow in desert and gravel, psilophytes grow in savanna and oxylophytes grow on acidic soil.
The first phylogenetic system of plant classification was proposed by
Engler
Engler and Prantl
Eichler
Wetlstein