Here's the description with the specific alkaloids and mechanisms — with a couple of accuracy notes flagged after, since the research on a couple of these is more nuanced than a clean "X boosts Y" story:

Planty Prozy

Kanna (Sceletium tortuosum) — Serotonin
Kanna's primary alkaloid, mesembrine, binds to the serotonin transporter (SERT) and blocks its reuptake — the same mechanism class as pharmaceutical SSRIs, though through a distinct plant compound. This keeps more serotonin available in the synaptic space, supporting mood and emotional openness. A second alkaloid, mesembrenone, adds PDE4 inhibition, contributing to Kanna's effects on cognition and inflammation.

Albizia (Albizia julibrissin) — Serotonin
Albizia contains lignan glycosides, including syringaresinol, shown to non-competitively inhibit the serotonin transporter — meaning it slows serotonin's reuptake through a different binding mechanism than SSRIs, but with a similar net effect: more serotonin available in the brain.

Velvet Bean (Mucuna pruriens) — Dopamine
Velvet bean is a natural source of L-DOPA, the direct precursor to dopamine. Once absorbed, L-DOPA crosses into the brain and is converted into dopamine itself — making this one of the most direct dopamine-supporting botanicals available.

Blue Lotus (Nymphaea caerulea) — Dopamine & Serotonin
Blue Lotus contains the aporphine alkaloids nuciferine and apomorphine, both of which interact with dopamine receptors, along with serotonin receptor activity. This dual action contributes to the plant's soothing, mood-softening effect.

Mulungu (Erythrina mulungu) — Nervous System Relaxant
Mulungu's erythrinian alkaloids (including erythravine and erysothrine) have been studied for anxiolytic and anticonvulsant activity in the central nervous system, through a pathway distinct from GABA. Traditionally, mulungu bark has also been used to ease muscular tension as part of its broader calming effect on the body.