A large growing Pachypodium species, aka the Madagascar Palm. (They are not palms; they are pachycaul (thick trunked) trees from Madagascar. this seems like a genetic link between lamerei and geayi. Flowers are white with yellow throats. Pretty uncommon pachy species! Deciduous, drops leaves in winter. Can get up to 20 feet tall and just as wide, but takes a long time. 1 gallon, seed grown.
As described by Huntington Botanical Gardens:
"As Jonas Luthy commented in his article describing this new pachypodium (C&SJ, Vol. 77:178 - 186, 2005), it is surprising that this tall, arborescent species could have eluded description for so long. The plants were first encountered by botanists at the beginning of the 20th century, but they were confused with P. geayi. The two species grow together and have similar cigar-shaped trunks with a crown of slender branches and similar leaves (though these are more densely white-tomentose beneath in mature P. mikea). The flowers, however, are distinctive. Those of P. geayi are distinct in having creamy yellow reflexed petals and exserted stamens while those of P. mikea are more like those of P. lamerei, white with a yellow throat and included stamens."