Turtle画树丛，50棵树，左侧的树向左倾斜，右侧的树向右倾斜。

完整代码如下：

import turtle
import random

def draw_tree(pos,hd,angle,len,init_len,level):    
    t.penup()
    t.goto(pos)
    t.pendown()
    t.setheading(hd)
    
    if pos[0]<0:t.lt(angle)
    else:t.rt(angle)
    
    t.fd(len)
    
    p1 = t.position()
    d1 = t.heading()
    
    t.penup()
    t.goto(pos)    
    t.setheading(hd)
    t.pendown()
    
    if pos[0]<0:t.lt(angle*2)
    else:t.rt(angle*2)
    t.fd(len)
    
    p2 = t.position()
    d2 = t.heading()
    
    if len>init_len-6*level:
        draw_tree(p1,d1,angle,len-6,init_len,level)
        draw_tree(p2,d2,angle,len-6,init_len,level)

        

t = turtle.Turtle()
turtle.screensize(800,600)
t.pencolor('black')
turtle.tracer(False)

for i in range(50):
    init_len = random.randint(30,60)
    level = random.randint(3,5)

    pos =  (random.randint(-400,400),random.randint(-300,300)) 
    t.setheading(90)
    hd = t.heading()
    draw_tree(pos,hd,15,init_len,init_len,level)
    t.penup()
    t.goto(pos)
    t.pendown()
    t.setheading(90)


turtle.exitonclick()