Leaves of the Red Mulberry Tree (morus rubra) -- notched or not?

Question

Looking at pictures of the leaves of red mulberry trees, some show leaves that are notched at the base, to make them more of a heart shape, and others show them without the notch.

My question is when are the leaves notched and when not? Are they two different species or what?

To clarify what I mean by the notch, consider a heart shape, such as in a valentine or a playing card. At the top of the heart, it curves inward. That's the notch. The stem of the leaf of the red mulberry tree is attached to the notch. so the leaf is like a heart on a stem. But my question is about the ones that aren't notched, and why not, and when not, etc.

Answer 1

Red mulberry leaves have different shapes. If you see a notch, it is not very significant. Have a look at the pictures here:

http://www.altavista.com/image/results?itag=ody&q=red+mulberry+leaf&kgs=1&kls=0

Answer 2

following are the photos of the leaf in question-

1)http://en.wikipedia.org/wiki/Image:Red_Mulberry_Leaf_Topside_600.jpg

2 ) http://en.wikipedia.org/wiki/Image:Red_Mulberry_Leaf_Underside_600.jpg

3 ) http://www.clemson.edu/extfor/publications/bul117/images/Morus_rubra.gif

4 ) http://www.uoguelph.ca/botany/research/evollab/mrubra2.jpg

5 ) http://www.sbs.utexas.edu/bio406d/images/pics/mor/Morus%20rubra%20leaves3.jpg

from the above photos it will be evident that notch or no notch is a minor variation displayed by the same species ,namely
Morus rubra or Red mulberry.

Real heart shape is found in the following--

1 )Dioscorea leaf
http://biotech.tipo.gov.tw/plantjpg/1/Dioscorea%20alata.jpg

http://en.wikipedia.org/wiki/Image:Wild_yam_in_woods_-_young_plants.jpg

2 ) Thespesia leaf
http://www.hibiscus.org/gfx/thespesia_leaves_top.jpg

http://www.malvaceae.info/Genera/Thespesia/Thesleaf1.jpg

Answer 3

Red mulberry leaves are alternate, thin, rounded or somewhat heart-shaped, toothed, pointed, 3 to 5 inches long, rough-hairy above and soft-hairy beneath. Leaves from juvenile tissue (early branches) are mitten-shaped or variously lobed (two to three lobes), while leaves from mature tissue (older, or upper-crown branches) are not lobed.