Plants starting with the syllable “Si”

Petrified forest wood

Silicisilvaxylon

Milk thistle

Silybum

Ivory Milk Thistle

Silybum eburneum

Also known as: Silver milk thistle

Spanish ivory thistle

Silybum eburneum subsp. hispanicus

Intermediate Milk Thistle

Silybum intermedium

White-flowered Milk Thistle

Silybum leucanthum

Spotted Milk Thistle

Silybum maculatum

Saint Mary's Milk Thistle

Silybum mariae

Blessed Milk Thistle

Silybum marianum

Typical milk thistle

Silybum marianum var. marianum

Morian Milk Thistle

Silybum morianum

Pygmy milk thistle

Silybum pygmaeum

Squarrose milk thistle

Silybum squarrosum

Gonzalo's Milk Thistle

Silybum ×gonzaloi

Simaba Tree

Simaba

African simaba

Simaba africana

Winged Simaba

Simaba alata

Bitter simaba

Simaba amara

Also known as: Simaba

Narrow-leaved Simaba

Simaba angustifolia

Sand calunga

Simaba arenaria

Aruba calunga

Simaba aruba

Bahia calunga

Simaba bahiensis

Bailey's Simaba

Simaba baileyana

Bicolor simaba

Simaba bicolor