\documentclass[border=5mm]{standalone}
\usepackage{luamplib}
\begin{document}
\mplibtextextlabel{enable}
\mplibshowlog{enable}
\begin{mplibcode}
% randomseed := uniformdeviate infinity;
randomseed := 134.7384;
r = 0.75; theta = 17;
vardef make_tree(expr bar) =
 save a; numeric a; a = abs(point 1 of bar - point 0 of bar);
 cutdraw bar withpen pencircle scaled (a/8);
 if a > 5:
   save s; pair s; s = 1/32 a * r * unitvector(direction 1 of bar) rotated 90;
   make_tree(
     bar shifted - point 0 of bar shifted s
     scaled (r + 1/16 normaldeviate) rotated (theta + 8 normaldeviate)
     shifted point 1 of bar
   );
   make_tree(
     bar shifted - point 0 of bar shifted -s
     scaled (r + 1/16 normaldeviate) rotated -(theta + 8 normaldeviate)
     shifted point 1 of bar
   );
 fi
enddef;
beginfig(1);
 for i=1 upto 4:
   picture T; T = image(make_tree(origin -- 40 up)); draw T shifted (170i, 0);
 endfor
 input show_name;
endfig;
\end{mplibcode}
\end{document}