There are actually lots and lots of leaf shapes — some with just minor differences between them — but the following are a few of the most common:

• Aciculate / acicular – needle-shaped – very narrow and pointed, rounded in cross section
• Cordate – heart-shaped – pointed apex, 2 rounded basal lobes
• Elliptic / elliptical – oval, widest at the middle of the blade, with curved margins and a pointed base and apex
• Flabellate – fan-shaped – semi-circular
• Hastate – spear-shaped – pointed, shaped like a spear point, with flaring pointed lobes at the base
• Lanceolate – lance-shaped – long (3-6x as long as it is wide) and widest below the middle of the blade
• Linear – long and very narrow, margins almost parallel, like a blade of grass
• Obcordate – reverse heart-shaped – with the stem attached at the tapering end
• Oblanceolate – reverse lanceolate – much longer than wide, with the widest portion above the middle of the blade
• Oblong – nearly rectangular, with almost parallel margins, around 2x as long as wide
• Obovate – teardrop-shaped – reverse ovate – widest above the middle of the blade, with the stem attached to the tapering end
• Orbiculate / orbicular – circular – with rounded sides
• Ovate – oval / egg-shaped – with a tapering point, widest below the middle of the blade near the petiole
• Reniform – kidney-shaped – oval with an inward curve on one side
• Rhomboid / rhombic – diamond-shaped – widest at the middle and with straight margins
• Runcinate – oblanceolate with lacerate margins
• Sagittate – arrowhead-shaped with lower lobes folded downwards or inwards
• Spatulate – spoon-shaped – broad flat end which tapers towards the base
• Triangular / deltoid – triangular, shaped roughly like an equilateral triangle (“deltoid” because it is shaped like the Greek letter delta)