To model the problem, we can use the equation based on the total number of tropical plants \( t \) divided by the number of greenhouses (5) equals the number of plants in each greenhouse (185). The equation can be set up as follows:
\[ \frac{t}{5} = 185 \]
Now, to solve for \( t \), we can multiply both sides of the equation by 5:
\[ t = 185 \times 5 \]
Calculating the right side:
\[ t = 925 \]
Thus, the total number of tropical plants in the shipment is 925 tropical plants.