simpler recursive code runs slower than iterative version of the same thing

I wrote this python code to give the Harmonic Series of a certain value n both recursively and iteratively. Here is the functions:

def H(n):
    if (n <= 0): raise ValueError("n must be bigger than 0.")
    if (n == 1): return 1
    else: return sum([1/x for x in range(1,n+1)])

def H_rec(n):
    if (n <= 0): raise ValueError("n must be bigger than 0.")
    if (n == 1): return 1
    else: return 1/n + H(n-1)

Then, when I run the code 10 times for each, I get the following times:

RECURSIVE TIMES [22.755768060684204, 17.231882095336914, 14.965636014938354, 14.277509927749634, 14.0553719997406, 13.788002014160156, 13.338942766189575, 13.72638201713562, 14.690818071365356, 14.236813068389893] 
RECURSIVE MEAN: 15.30671260356903
ITERATIVE TIMES [15.093524932861328, 12.801156759262085, 13.350629091262817, 13.806081056594849, 13.29387378692627, 13.876484870910645, 12.934008121490479, 13.859009981155396, 13.350301027297974, 13.590226888656616] 
ITERATIVE MEAN: 13.595529651641845

The code is supposed to find H_rec(100000000) and H(100000000), which are fairly big numbers.

I don't understand exactly why the recursive definition takes longer when the way it's defined seems to require less computation. The iterative one requires forming a list and finding its sum, while the recursive one just sums 1/n + H(n-1).

What is so misleading about this recursion? Why is it slow?