Let the number of geraniums be denoted by \(G\), roses by \(R\), and lilies by \(L\). We have the following conditions:

1. \(G + R + L = 25\)

2. \(G \geq 11\)

3. \(R = L\)

From condition 3, we have \(R = L\), so \(G + 2R = 25\).

We consider the possible values for \(G\):

1. \(G = 11\): Then \(11 + 2R = 25\) gives \(R = 7\) and \(L = 7\). The number of ways to choose the flowers is \(\binom{15}{11} \times \binom{10}{7} \times \binom{8}{7} = 1310400\).
2. \(G = 13\): Then \(13 + 2R = 25\) gives \(R = 6\) and \(L = 6\). The number of ways to choose the flowers is \(\binom{15}{13} \times \binom{10}{6} \times \binom{8}{6} = 617400\).
3. \(G = 15\): Then \(15 + 2R = 25\) gives \(R = 5\) and \(L = 5\). The number of ways to choose the flowers is \(\binom{15}{15} \times \binom{10}{5} \times \binom{8}{5} = 14112\).

Adding these possibilities gives the total number of selections:

\(1310400 + 617400 + 14112 = 1941912\).